diff --git a/config/control_command.yaml b/config/control_command.yaml
index 5cba715..69d7156 100644
--- a/config/control_command.yaml
+++ b/config/control_command.yaml
@@ -124,7 +124,7 @@ register_keys:
   target_reid_gap_threshold: 0.10
   target_reid_min_crop_area: 2000.0
   target_reid_max_crop_aspect_ratio: 0.90
-  target_reid_feature_update_interval: 5
+  target_reid_feature_update_interval: 3
   target_reid_lost_timeout_frames: 150
   target_reid_gallery_size: 8
   target_reid_input_height: 256
diff --git a/src/target_observation_processing.cpp b/src/target_observation_processing.cpp
index fb4908c..21354d1 100644
--- a/src/target_observation_processing.cpp
+++ b/src/target_observation_processing.cpp
@@ -748,6 +748,7 @@ std::vector<int> TargetObservationProcessor::bind_and_update_tracks(
     // Only brand-new unmatched rows go through the consecutive-hit gate in
     // Phase 4 before receiving a fresh stable_id.
     bool reid_recovery_attempted = false;
+    std::vector<bool> suppress_new_sid(static_cast<size_t>(row_count), false);
     for (int i = 0; i < row_count; ++i) {
         if (stable_ids[static_cast<size_t>(i)] >= 0) {
             continue;
@@ -855,6 +856,60 @@ std::vector<int> TargetObservationProcessor::bind_and_update_tracks(
         }
     }
 
+    // Phase 3.75: duplicate suppression. If an unbound row strongly matches
+    // an already claimed stable_id, treat it as a duplicate ByteTrack split
+    // of an existing person instead of allocating a new stable_id.
+    //
+    // Typical failure mode:
+    //   raw 1 -> sid0, raw 2 -> sid1, then ByteTrack temporarily emits raw 3
+    //   for the same person as sid0 while raw 1 is still alive.
+    // Without this guard, raw 3 would stay unbound, accumulate pending hits,
+    // and eventually get promoted to a brand-new sid2 even though its ReID
+    // is almost identical to sid0. Here we suppress that path.
+    for (int i = 0; i < row_count; ++i) {
+        if (stable_ids[static_cast<size_t>(i)] >= 0) {
+            continue;
+        }
+        const ReIDFeature& feature = features_by_row[static_cast<size_t>(i)];
+        if (feature.empty()) {
+            continue;
+        }
+
+        int best_sid = -1;
+        float top1 = -1.0f;
+        float top2 = -1.0f;
+        for (const auto& kv : tracks_) {
+            if (kv.second.gallery.empty()) {
+                continue;
+            }
+            const float sim = kv.second.gallery.best_similarity(feature);
+            if (sim > top1) {
+                top2 = top1;
+                top1 = sim;
+                best_sid = kv.first;
+            } else if (sim > top2) {
+                top2 = sim;
+            }
+        }
+
+        if (best_sid < 0) {
+            continue;
+        }
+        if (!taken_sids.count(best_sid)) {
+            continue;  // free sids are handled by Phase 3 ReID recovery
+        }
+        if (top1 < config_.reid_match_threshold) {
+            continue;
+        }
+        if (top2 >= 0.0f && (top1 - top2) < config_.reid_gap_threshold) {
+            continue;
+        }
+
+        const int raw_id = static_cast<int>(tracks(i, 4));
+        pending_raw_ids_.erase(raw_id);
+        suppress_new_sid[static_cast<size_t>(i)] = true;
+    }
+
     // Phase 4: allocate a fresh stable_id for rows that still have no match.
     // Apply the confirmed-track gate: a ByteTrack raw_id must show up for
     // `reid_confirm_hits_before_allocate` consecutive frames before getting
@@ -866,6 +921,9 @@ std::vector<int> TargetObservationProcessor::bind_and_update_tracks(
         if (stable_ids[static_cast<size_t>(i)] >= 0) {
             continue;
         }
+        if (suppress_new_sid[static_cast<size_t>(i)]) {
+            continue;
+        }
         const int raw_id = static_cast<int>(tracks(i, 4));
         auto [pit, inserted] = pending_raw_ids_.try_emplace(raw_id);
         PendingRaw& pending = pit->second;