$title multiple $unLoads of the same item are OK (UNLOAD5,SEQ=54)
variable x; parameter a;

a   = 2;
x.l = 1;

$gdxOut gdx1
$unLoad x x.l x.up x.l = x.garb x.l=y x= x
$unLoad a a a=b a=a
$unLoad 
$gdxOut
$gdxIn gdx1
$load