Remove Duplicate values in a variable

IF BELOW ARE THE !COLL VARIABLES

$!COLL[1] = SST-00053/DATUM
$!COLL[2] = SST-00053/SREF
$!COLL[3] = SST-00054/DATUM
$!COLL[4] = SST-00054.1
$!COLL[5] = SST-00055.1
$!COLL = SST-00058.1
$!COLL[7] = SST-00056.1
$!COLL[7] = SST-00058/DATUM


My result should be
SST-00053
SST-00054
SST-00055
SST-00056
SST-00058

IF BELOW ARE THE !COLL VARIABLES

$!COLL[1] = SST-00053/DATUM
$!COLL[2] = SST-00053/SREF
$!COLL[3] = SST-00054/DATUM
$!COLL[4] = SST-00054.1
$!COLL[5] = SST-00055.1
$!COLL = SST-00058.1
$!COLL[7] = SST-00056.1
$!COLL[7] = SST-00058/DATUM


My result should be
SST-00053
SST-00054
SST-00055
SST-00056
SST-00058