Neither one of them makes stocks. They source stocks and bundle kit parts. There are very few places that actually make pantograph stocks. There is a good chance it does not matter who the retailer actually is.
I have received two unusable stocks in a row from the same vendor. I gave up and built my Hawken from a plank.
I expect that any gun I make has perfect inletting and correct parts placement. Some people only want a gun that shoots. My definition of "usable" may be different than others'.
Unless you are using the best of the best, Kibler and Chambers, building from a plank is the way to go. You can make sure the layout and design is correct for your parts and the design is what you want. Mucking around with a messed up precarve is more frustration and likely more work than building from a plank. It MAY take longer but the result will likely be better.