Index: trunk/src/buffer.c
===================================================================
--- trunk/src/buffer.c	(revision 29974)
+++ trunk/src/buffer.c	(revision 29975)
@@ -133,6 +133,13 @@
 
 	/* when an edit-object is moved to buffer, the corresponding subc obj needs to be moved too */
 	if (subc != NULL) {
+		/* make sure the same subc is not copied twice by detecting a copy already done from the same subc to the same buffer */
+		pcb_subc_t *bsc;
+		gdl_iterator_t it;
+		subclist_foreach(&ctx->buffer.dst->subc, &it, bsc) {
+			if (bsc->copied_from_ID == subc->ID)
+				return 1;
+		}
 		pcb_subcop_add_to_buffer(ctx, subc);
 		return 1;
 	}
Index: trunk/src/obj_subc.c
===================================================================
--- trunk/src/obj_subc.c	(revision 29974)
+++ trunk/src/obj_subc.c	(revision 29975)
@@ -838,6 +838,8 @@
 	else
 		sc->ID = pcb_create_ID_get();
 
+	sc->copied_from_ID = src->ID;
+
 	minuid_cpy(sc->uid, src->uid);
 	pcb_subc_reg(dst, sc);
 
Index: trunk/src/obj_subc.h
===================================================================
--- trunk/src/obj_subc.h	(revision 29974)
+++ trunk/src/obj_subc.h	(revision 29975)
@@ -57,6 +57,7 @@
 	int part_changed_inhibit;
 	unsigned part_changed_bbox_dirty:1; /* part_changed_inhibit_dec() should recalculate the bbox */
 	unsigned auto_termname_display:1; /* display bit, not saved or loaded, only toggled by Display() on subc */
+	long int copied_from_ID; /* temporary storage during operation: if a subc is a copy of another subc in the same operation, keep the ID of the original subc to avoid duplicate copies */
 	gdl_elem_t link;
 };