The Mario and Donkey Kong game series have the same roots - they started the same way, and have split up from each other into seperate game series later - agreed. This does not, however mean that they can suddenly start having different continuity, i.e. they can't contradict each other in terms of the events that happened when they were both part of the same series. They're in the same 'world', if you like. The only way the continuity of both can work is if they compliment each other.
Also, if you find two series of games that are closer connected, let me know.
Also-also, Mario appears in DKC2 - but that's besides the point...
~Waddle Dedede @
www.the-warp-zone.com