Index: pbx.c
===================================================================
RCS file: /usr/cvsroot/asterisk/pbx.c,v
retrieving revision 1.284
diff -u -r1.284 pbx.c
--- pbx.c	13 Oct 2005 23:35:57 -0000	1.284
+++ pbx.c	14 Oct 2005 22:01:05 -0000
@@ -5885,15 +5885,24 @@
 {
 	struct ast_var_t *newvariable;
 	struct varshead *headp;
-
+	char *nametail = name;
 
 	if (name[strlen(name)-1] == ')')
 		return ast_func_write(chan, name, value);
 
 	headp = (chan) ? &chan->varshead : &globals;
 
+	/* For comparison purposes, we have to strip leading underscores */
+	if (nametail[0] == '_') {
+		if (nametail[1] == '_') {
+			nametail += 2;
+		} else {
+			nametail += 1;
+		}
+	}
+
 	AST_LIST_TRAVERSE (headp, newvariable, entries) {
-		if (strcasecmp(ast_var_name(newvariable), name) == 0) {
+		if (strcasecmp(ast_var_name(newvariable), nametail) == 0) {
 			/* there is already such a variable, delete it */
 			AST_LIST_REMOVE(headp, newvariable, entries);
 			ast_var_delete(newvariable);