In the last issue of the SCD Standard Catalog ( 2012)the Mantle variation for the 1952 set was listed, along with the Robinson and Thompson. On all three it lists the variation as the stitching on the back. But there are also front differences on the Mantle, for example a wavy or straight star line, a clipped or full e on the auto, tails or not on the upper borders and pixel or not on left. Here are mine;
I don't think it is included in the PSA master set list
Larry S ( sflayank) may have infor on your other card