I am agreeing with 4Dr4g0n on the point stress issue. If it were me I would throw a piece of 3/4" plywood (or something similar and possibly more rot resistant) between the two tanks to even out the stresses and weight. Better safe than sorry!

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26 Gal Bow-Front, 20 Gal Regular, 10 Gal regular
Some day I'll have a big tank...