But if they will fuse back together I’m not sure.
As long as there is a line of cambium between the two, they will eventually fuse (this is how grafting works). However, it can be 3 to 5 years to produce good mechanical strength (which comes from producing a new continuous shell of wood across the gap). But I agree that it may not be worthwhile, long term.
Nevertheless, it is a 'growable' tree, just not what you paid for. I would consider a large partial refund instead of replacement, if that is a possibility.