diff --git a/include/osmocom/msc/paging.h b/include/osmocom/msc/paging.h
index 4de679d..f8ebf9e 100644
--- a/include/osmocom/msc/paging.h
+++ b/include/osmocom/msc/paging.h
@@ -40,6 +40,7 @@
 struct paging_request *paging_request_start(struct vlr_subscr *vsub, enum paging_cause cause,
 					    paging_cb_t paging_cb, struct gsm_trans *trans,
 					    const char *label);
+void paging_request_join_vsub(struct vlr_subscr *keep_vsub, struct vlr_subscr *discarding_vsub);
 void paging_request_remove(struct paging_request *pr);
 
 void paging_response(struct msc_a *msc_a);
diff --git a/include/osmocom/msc/vlr.h b/include/osmocom/msc/vlr.h
index 86a72f2..a7707fd 100644
--- a/include/osmocom/msc/vlr.h
+++ b/include/osmocom/msc/vlr.h
@@ -257,6 +257,8 @@
 	/* notify MSC/SGSN that the given subscriber has been associated
 	 * with this msc_conn_ref */
 	int (*subscr_assoc)(void *msc_conn_ref, struct vlr_subscr *vsub);
+	/* notify MSC that the given subscriber is no longer valid */
+	void (*subscr_inval)(void *msc_conn_ref, struct vlr_subscr *vsub);
 };
 
 /* An instance of the VLR codebase */
diff --git a/src/libmsc/gsm_04_08.c b/src/libmsc/gsm_04_08.c
index 70faf95..17350fa 100644
--- a/src/libmsc/gsm_04_08.c
+++ b/src/libmsc/gsm_04_08.c
@@ -1572,6 +1572,24 @@
 	return 0;
 }
 
+static void msc_vlr_subscr_inval(void *msc_conn_ref, struct vlr_subscr *vsub)
+{
+	/* Search vsub backwards to make sure msc_conn_ref is a valid msc_a instance. */
+	struct msub *msub;
+	OSMO_ASSERT(vsub);
+	llist_for_each_entry(msub, &msub_list, entry) {
+		struct msc_a *msc_a;
+		if (msub->vsub != vsub)
+			continue;
+
+		msc_a = msub_msc_a(msub);
+		if (msc_a)
+			msc_a_release_cn(msc_a);
+
+		msub->vsub = NULL;
+	}
+}
+
 /* operations that we need to implement for libvlr */
 const struct vlr_ops msc_vlr_ops = {
 	.tx_auth_req = msc_vlr_tx_auth_req,
@@ -1586,6 +1604,7 @@
 	.tx_mm_info = msc_vlr_tx_mm_info,
 	.subscr_update = msc_vlr_subscr_update,
 	.subscr_assoc = msc_vlr_subscr_assoc,
+	.subscr_inval = msc_vlr_subscr_inval,
 };
 
 struct msgb *gsm48_create_mm_serv_rej(enum gsm48_reject_value value)
diff --git a/src/libmsc/paging.c b/src/libmsc/paging.c
index 9845f99..9b3dad5 100644
--- a/src/libmsc/paging.c
+++ b/src/libmsc/paging.c
@@ -120,6 +120,34 @@
 	return pr;
 }
 
+/* Two subscribers (e.g. an old TMSI and a new TMSI) turn out to have the same identity, so in order to discard one of
+ * them, transfer any pending Paging requests to the vsub that will survive. */
+void paging_request_join_vsub(struct vlr_subscr *keep_vsub, struct vlr_subscr *discarding_vsub)
+{
+	struct paging_request *pr;
+
+	if (!discarding_vsub->cs.is_paging)
+		return;
+
+	/* transfer all Paging Response callbacks */
+	while ((pr = llist_first_entry_or_null(&discarding_vsub->cs.requests, struct paging_request, entry))) {
+		llist_del(&pr->entry);
+		talloc_steal(keep_vsub, pr);
+		llist_add_tail(&pr->entry, &keep_vsub->cs.requests);
+	}
+
+	/* make sure a Paging use count is present on keep_vsub, if needed */
+	if (!keep_vsub->cs.is_paging && !llist_empty(&keep_vsub->cs.requests)) {
+		vlr_subscr_get(keep_vsub, VSUB_USE_PAGING);
+		keep_vsub->cs.is_paging = true;
+	}
+
+	/* Already made sure at the top of this function that discarding_vsub->cs.is_paging == true */
+	discarding_vsub->cs.is_paging = false;
+	osmo_timer_del(&discarding_vsub->cs.paging_response_timer);
+	vlr_subscr_put(discarding_vsub, VSUB_USE_PAGING);
+}
+
 void paging_request_remove(struct paging_request *pr)
 {
 	struct gsm_trans *trans = pr->trans;
diff --git a/src/libvlr/vlr.c b/src/libvlr/vlr.c
index e2e02bf..cb5794f 100644
--- a/src/libvlr/vlr.c
+++ b/src/libvlr/vlr.c
@@ -36,6 +36,7 @@
 #include <osmocom/msc/vlr.h>
 #include <osmocom/msc/debug.h>
 #include <osmocom/msc/gsup_client_mux.h>
+#include <osmocom/msc/paging.h>
 
 #include <netinet/in.h>
 #include <arpa/inet.h>
@@ -272,7 +273,8 @@
 
 	llist_for_each_entry(vsub, &vlr->subscribers, list) {
 		if (vlr_subscr_matches_imsi(vsub, imsi)) {
-			vlr_subscr_get_src(vsub, use, file, line);
+			if (use)
+				vlr_subscr_get_src(vsub, use, file, line);
 			return vsub;
 		}
 	}
@@ -577,11 +579,63 @@
 	return vsub;
 }
 
+static void dedup_vsub(struct vlr_subscr *exists, struct vlr_subscr *vsub)
+{
+	struct vlr_instance *vlr = exists->vlr;
+	int i;
+	int j;
+	LOGP(DVLR, LOGL_NOTICE,
+	     "There is an existing subscriber for IMSI %s used by %s, replacing with new VLR subscr: %s used by %s\n",
+	     exists->imsi, osmo_use_count_to_str_c(OTC_SELECT, &exists->use_count),
+	     vlr_subscr_name(vsub),
+	     osmo_use_count_to_str_c(OTC_SELECT, &vsub->use_count));
+
+	/* Take over some state from the previous vsub */
+	paging_request_join_vsub(vsub, exists);
+	if (!vsub->msisdn[0])
+		OSMO_STRLCPY_ARRAY(vsub->msisdn, exists->msisdn);
+	if (!vsub->name[0])
+		OSMO_STRLCPY_ARRAY(vsub->name, exists->name);
+	/* Copy valid auth tuples we may already have, to reduce the need to ask for new ones from the HLR */
+	for (i = 0; i < ARRAY_SIZE(exists->auth_tuples); i++) {
+		if (exists->auth_tuples[i].key_seq == VLR_KEY_SEQ_INVAL)
+			continue;
+		for (j = 0; j < ARRAY_SIZE(vsub->auth_tuples); j++) {
+			if (vsub->auth_tuples[j].key_seq != VLR_KEY_SEQ_INVAL)
+				continue;
+			vsub->auth_tuples[j] = exists->auth_tuples[i];
+		}
+	}
+
+	if (exists->msc_conn_ref)
+		LOGVSUBP(LOGL_ERROR, vsub,
+			 "There is an existing VLR entry for this same subscriber with an active connection."
+			 " That should not be possible. Discarding old subscriber entry %s.\n",
+			 exists->imsi);
+
+	if (vlr->ops.subscr_inval)
+		vlr->ops.subscr_inval(exists->msc_conn_ref, exists);
+	vlr_subscr_free(exists);
+}
+
 void vlr_subscr_set_imsi(struct vlr_subscr *vsub, const char *imsi)
 {
+	struct vlr_subscr *exists;
 	if (!vsub)
 		return;
 
+	/* If the same IMSI is already set, nothing changes. */
+	if (!strcmp(vsub->imsi, imsi))
+		return;
+
+	/* We've just learned about this new IMSI, our primary key in the VLR. make sure to invalidate any prior VLR
+	 * entries for this IMSI. */
+	exists = vlr_subscr_find_by_imsi(vsub->vlr, imsi, NULL);
+
+	if (exists)
+		dedup_vsub(exists, vsub);
+
+	/* Set the IMSI on the new subscriber, here. */
 	if (OSMO_STRLCPY_ARRAY(vsub->imsi, imsi) >= sizeof(vsub->imsi)) {
 		LOGP(DVLR, LOGL_NOTICE, "IMSI was truncated: full IMSI=%s, truncated IMSI=%s\n",
 		       imsi, vsub->imsi);
diff --git a/tests/msc_vlr/msc_vlr_test_rest.err b/tests/msc_vlr/msc_vlr_test_rest.err
index e649325..fae302f 100644
--- a/tests/msc_vlr/msc_vlr_test_rest.err
+++ b/tests/msc_vlr/msc_vlr_test_rest.err
@@ -467,7 +467,6 @@
 DMM IDENTITY RESPONSE: IMSI-901700000004620
 DVLR set IMSI on subscriber; IMSI=901700000004620 id=901700000004620
 DVLR vlr_lu_fsm(TMSI-0x23422342:GERAN-A:LU){VLR_ULA_S_WAIT_IMSI}: Received Event VLR_ULA_E_ID_IMSI
-DVLR set IMSI on subscriber; IMSI=901700000004620 id=901700000004620
 DVLR vlr_lu_fsm(TMSI-0x23422342:GERAN-A:LU){VLR_ULA_S_WAIT_IMSI}: vlr_loc_upd_node1_pre()
 DVLR vlr_lu_fsm(TMSI-0x23422342:GERAN-A:LU){VLR_ULA_S_WAIT_IMSI}: vlr_loc_upd_node1()
 DVLR vlr_lu_fsm(TMSI-0x23422342:GERAN-A:LU){VLR_ULA_S_WAIT_IMSI}: vlr_loc_upd_post_auth()