Is it possible to use " every second Saturday" instead of "every other Saturday"?
Personally, I would interpret "every second Saturday" to implicitly mean "every second Saturday [of the month]".
However, I think this is more an error of interpretation, than it actually being incorrect.
"Every other Saturday" seems to be immune to such misinterpretations, and I'd favor using that instead, if only to prevent possible misunderstandings.