which lipos- mmm combo

hi all .thanks for your advice guys, lipos are new to me so id be lost without you're advice so thanks all . just one more thing this running 2 packs in parallel, is traxxasbasher right if i had 2 20c 5s 5000mah packs parallel id have 10,000mah but still 20c? i dont get it why not? twice the mah surley 20c x2???? thanks guys this is the only thing im not sure of now and nearly ready to order batts and charger yay bye...