Well, it's not really that bad, I did it for years with NO problems. A few points to ponder:
1) Are you ready to be a parent to 20ish babies a year? I personally love it but can take a bit of work to take care of and sell.
2) If one gets sick, you really should be able to seperate. So additional caging is a must.
3) What if they don't get along? Again, not very probable but possible?
4) DO NOT FEED TOGETHER!!!!! DUH
5) Also, they should be similar size.
Even with all that, one could eat the other, I saw some pics a while back on the boa forum where two sibling boas had each been fed a mouse, then put back into one tub. The smaller one proceeded to eat the larger one, not a pretty picture.
Bottom line, better to house seperately. Likelyhood of problems if housed together is actually quite small but there is a chance!
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Thanks,
Dave Colling

www.rainbows-r-us-reptiles.com
0.1 Wife (WC)
0.2 kids (CBB)
LOL, to many snakes to list, last count:
10.22 BRB
10.15 BCI
And those are only the breeders 
lots.lots.lots feeder mice and rats 