I'm running two 2s 7.4 Lipos in series to make 4s and I have a 7.4 saddle pak, can I add the two 1s packs that make the saddle pak to the the two 2s packs I'm running now wired in series to make 6s?

yup , just add it in series

Has long has they are the same Mah?

A shorty pack would of been better,if i was the same,be lighter that two 1s I would think,