diff --git a/lib/addons/prebid/analytics.test.ts b/lib/addons/prebid/analytics.test.ts
index 64bba2c6..09f8c63a 100644
--- a/lib/addons/prebid/analytics.test.ts
+++ b/lib/addons/prebid/analytics.test.ts
@@ -431,6 +431,41 @@ describe("OptablePrebidAnalytics", () => {
       expect(result.optableSources).toEqual(["uidapi.com", "id5-sync.com"]);
       expect(result.liveintentEIDs).toEqual(["uidapi.com"]);
     });
+
+    it("keeps an Optable EID when a later non-Optable EID shares its source", async () => {
+      const result = await analytics.toWitness(
+        {
+          auctionId: "auction-shared-source",
+          bidderRequests: [
+            {
+              bidderCode: "bidder1",
+              bidderRequestId: "req-1",
+              ortb2: {
+                site: { domain: "example.com" },
+                user: {
+                  ext: { eids: [{ inserter: "optable.co", matcher: "uid2", source: "uidapi.com" }] },
+                  eids: [{ source: "uidapi.com", uids: [{ id: "li", ext: { provider: "liveintent.com" } }] }],
+                },
+              },
+              bids: [],
+            },
+          ],
+          bidsReceived: [],
+          noBids: [],
+          timeoutBids: [],
+        },
+        []
+      );
+
+      expect(result.bidderRequests[0]).toMatchObject({
+        optableTargetingDone: true,
+        optableMatchers: ["uid2"],
+        optableSources: ["uidapi.com"],
+      });
+      expect(result.optableMatchers).toEqual(["uid2"]);
+      expect(result.optableSources).toEqual(["uidapi.com"]);
+      expect(result.optableTargetingDone).toBe("1");
+    });
   });
 
   describe("trackAuctionEnd", () => {
diff --git a/lib/addons/prebid/analytics.ts b/lib/addons/prebid/analytics.ts
index 490e3bd1..97f1b86f 100644
--- a/lib/addons/prebid/analytics.ts
+++ b/lib/addons/prebid/analytics.ts
@@ -393,8 +393,8 @@ class OptablePrebidAnalytics {
       const { bidderCode, bidderRequestId, bids = [] } = br;
       const domain = br.ortb2.site?.domain ?? "unknown";
       const allEids = [...(br.ortb2.user?.ext?.eids ?? []), ...(br.ortb2.user?.eids ?? [])];
-      // Deduplicate EIDs by source
-      const eids = Array.from(new Map(allEids.map((eid: any) => [eid.source, eid])).values());
+      // Deduplicate EIDs by source and inserter, so another inserter's EID can't hide Optable's
+      const eids = Array.from(new Map(allEids.map((eid: any) => [`${eid.source}|${eid.inserter}`, eid])).values());
 
       // Optable EIDs
       const optableEIDS = eids.filter((e: { inserter: string }) => e.inserter === "optable.co");