diff --git a/src/rntuple.cpp b/src/rntuple.cpp
index 50075cc..720370e 100644
--- a/src/rntuple.cpp
+++ b/src/rntuple.cpp
@@ -87,6 +87,7 @@ void gather_ntuple_metadata(Arena *arena, RMicroFileReader &reader, const RNTupl
   fprintf(stderr, "Loading pages...\n");
   
   u64 n_pages = 0;
+  u64 n_duplicate_page_ranges = 0;
   u64 n_elems = 0;
   u64 tot_page_comp_size = 0;
   Page_Info_Node *pinfo_head = nullptr, *pinfo_tail = nullptr;
@@ -124,6 +125,8 @@ void gather_ntuple_metadata(Arena *arena, RMicroFileReader &reader, const RNTupl
           pinfo->is_first_in_cluster = true;
         }
 
+        b8 duplicate = false;
+        
         if (UNLIKELY(!pinfo_head)) {
           // first node inserted
           assert(!pinfo_tail);
@@ -146,6 +149,11 @@ void gather_ntuple_metadata(Arena *arena, RMicroFileReader &reader, const RNTupl
           b8 pinfo_is_after_last = pinfo->range.start >= last_inserted_pinfo->range.end();
           if (pinfo_is_after_last) {
             for (Page_Info_Node *node = last_inserted_pinfo->next; node; node = node->next) {
+              // sanity check for duplicate pages
+              if (pinfo->range.start == node->range.start) {
+                duplicate = true;
+                break;
+              }
               // check if `pinfo` fits right before the node we're looking at
               if (pinfo->range.end() <= node->range.start) {
                 Page_Info_Node *prev = node->prev;
@@ -163,6 +171,11 @@ void gather_ntuple_metadata(Arena *arena, RMicroFileReader &reader, const RNTupl
             }
           } else {
             for (Page_Info_Node *node = last_inserted_pinfo; node; node = node->prev) {
+            // sanity check for duplicate pages
+              if (pinfo->range.start == node->range.start) {
+                duplicate = true;
+                break;
+              }
               // check if `pinfo` fits right before the node we're looking at
               if (pinfo->range.end() <= node->range.start) {
                 Page_Info_Node *prev = node->prev;
@@ -180,7 +193,12 @@ void gather_ntuple_metadata(Arena *arena, RMicroFileReader &reader, const RNTupl
             }
           }
 
-          assert(inserted);
+          assert(inserted != duplicate);
+        }
+
+        if (duplicate) {
+          ++n_duplicate_page_ranges;
+          continue;
         }
 
         last_inserted_pinfo = pinfo;
@@ -195,7 +213,8 @@ void gather_ntuple_metadata(Arena *arena, RMicroFileReader &reader, const RNTupl
   chr::time_point end_t = chr::high_resolution_clock::now();
   u64 time_spent_ms = chr::duration_cast<chr::milliseconds>(end_t - start_t).count();
 
-  fprintf(stderr, "Loaded %lu pages in %lu ms.\nGenerating groups...\n", n_pages, time_spent_ms);
+  fprintf(stderr, "Loaded %lu pages in %lu ms (%lu duplicates).\nGenerating groups...\n", 
+          n_pages, time_spent_ms, n_duplicate_page_ranges);
 
   // Create page groups and chunks.
   // Each page group is a grouping of GROUP_SIZE page infos whose range is equal to the combined ranges