Index: /trunk/psModules/src/imcombine/pmSubtractionStamps.c
===================================================================
--- /trunk/psModules/src/imcombine/pmSubtractionStamps.c	(revision 13377)
+++ /trunk/psModules/src/imcombine/pmSubtractionStamps.c	(revision 13378)
@@ -60,4 +60,5 @@
     PS_ASSERT_INT_LARGER_THAN(image->numRows, 2 * border, NULL);
 
+    maskVal |= used;                    // Make sure we don't get stamps we've already used
     int xNumStamps = (image->numCols - 2 * border) / spacing + 1; // Number of stamps in x
     int yNumStamps = (image->numRows - 2 * border) / spacing + 1; // Number of stamps in y
@@ -138,4 +139,8 @@
                 stamp->status = fluxBest > threshold ? PM_SUBTRACTION_STAMP_CALCULATE :
                     PM_SUBTRACTION_STAMP_NONE;
+                if (stamp->status == PM_SUBTRACTION_STAMP_CALCULATE) {
+                    psTrace("psModules.imcombine", 5, "Found stamp in region (%d,%d): %d,%d\n",
+                            i, j, stamp->x, stamp->y);
+                }
             }
         }