I bought a Toto Drake 2 piece toilet that is described on Amazon as being 1.6 GPF. When the tank and bowl arrived in separate boxes, the bowl had some shattered ceramic. I am trying to make sure I re-ordered the correct bowl. I noticed the bowl's packing slip showed it was rated 1.28 GPF. Upon contacting the seller, the seller said that the 1.6 GPG in the Amazon description was just for the tank, not the bowl, even though there is no mention that the 1.6 is just for the tank. He said that the 1.6 GPF tank goes with the 1.28 GPF bowl. Does this make sense? Could a 1.28 bowl restrict the flow of a 1.6 tank?
Any extra water that leaves the tank will just go down the toilet as extra water, so no worries there. If you're concerned about the extra water, you could always either lower the tank fill level, or put a brick or something else dense and non-porus in the tank to take up some of the space the water would use.
Toilets are a complete system, particularly the low-flush units. So I'd have to suspect your seller is selling random parts (pulled from the defective bin?) rather than complete toilets, cue "shady selling practices on Amazon" theme music. Contact Toto for the definitive answer to that question rather than your seller, who is very likely not an authorized dealer, which is another question you can ask them. Has global trade dipped to the level of counterfeit "high end" toilets? Quite possibly.
The 1.28 won't "restrict" the 1.6 tank, but the 1.6 tank may not operate the 1.28 bowl correctly as its matching tank would, even though it's dumping in more water. The subtle engineering differences that make todays low-flush toilets actually work as opposed to the crudely retrofit 5 gallon per-flush toilets made into 3 gallon per flush water-savers that often required two water-saving 3 gallon flushes to flush (thus using an extra gallon) are not obvious to the casual user, but may be important to the toilet working as designed.
i.e. my 1.28 has a tank both taller and narrower than "old-fangled" toilets, so it uses less water, but the flush has more pressure from the taller tank.