I need confirmation on something. Will a standard 29 gallon tank fit on an aquarium stand that holds a 20 gallon long?

Both are All Glass\Aqeon Glass Tanks. The foot print is the same, 30" x 12". The 29 is 6" higher or 18" instead of 12".

I found an Aqeon 29 Gallon Standard tank on clearance at Petco today for $49.50. But the young gentleman that was running the aquarium supply area today told me it wouldn't be safe to put the 29 on the 20 long wood stand, which makes no sense to me because the foot print is the same.

Input would be appreciated. Thanks in advance.