A friend and I are using the same dump of Tatsunoko vs. Capcom: Ultimate All-Stars and the same version of Dolphin (3.0-898). For some reason, his client recognized the ISO title as TATSUNOKO VS. CAPCOM ULTIMATE ALL-STARS, whereas mine shows up as TATSUNOKO VS. CAPCOM with ULTIMATE ALL-STARS under the notes. Because of this, we can't play online. Can you guys just change it so that it enforces consistency by game ID instead?
Both try redownloading the latest build from the website, and copying one version of the dump to both computers without changing anything. I don't know what the issue is, but, for example, if you both got the same version, but from different branches, or compiled by different people, there may be some issue there. Also, if the right bit in the banner file in the .iso changed from 0 to 1 during copying, it could mess all this up.
i would bet that one of you has a banner and the other doesn't. have the person who has the banner export the save and import it on the other computer
Try to boot the game locally at least one time to generate banner files for both computers...