I doubt it is the same mold from two different manufacturers. The same company likely produced them both, the header and backer are just generic ones that came with a few different toys. The header only reads "kaiju series" so that was used on a lot of figures.

For comparison, you can see the blue-chested version on backing with the other artwork here:



And as well for reference, this photo of a Lion Maru boot (borrowed from Lixx) also has the second artwork style:



If anything would make a substantial price difference, it would be whether the figure had the removable mask or not, but as far as I am aware, only the gold chested ones have it, while the regular versions came in both gold and blue.