Don't mix any vitamin powder in with the CGD and only mix in baby food if you absolutely have to. I would advise not using baby food at all, and hand feeding the plain CGD until they take it on their own.

Are both geckos the same size? How old are they?

Try handfeeding them plain CGD every 2-3 days for 2 weeks. If they are not both eating it by that time, separate the one that isn't eating it into a small kritter keeper and continue to hand feed him until he eats it on his own. Sometimes they start slow and sometimes a larger or more dominate cage mate prevents them from eating.