--- chan_dahdi.c	2010-06-02 16:54:31.000000000 -0300
+++ chan_dahdi.c	2010-06-02 19:22:32.000000000 -0300
@@ -12030,6 +12030,16 @@
 		if (conf->chan.vars) {
 			struct ast_variable *v, *tmpvar;
 	                for (v = conf->chan.vars ; v ; v = v->next) {
+				int skip = 0;
+				for (tmpvar = tmp->vars ; tmpvar; tmpvar = tmpvar->next)
+					if(!strcasecmp(v->name, tmpvar->name)) {
+						/* for duplicate entries only take the first in the list */
+						skip = 1;
+						break;
+					}
+				if(skip) 
+				  continue;
+
         	                if ((tmpvar = ast_variable_new(v->name, v->value, v->file))) {
                 	                tmpvar->next = tmp->vars;
                         	        tmp->vars = tmpvar;