New construction- tiling over incorrect tile in shower

We have a newly constructs condo. The contractor installed the incorrect tile on the floors in two showers. They are going to simply tile over the tile they just installed. Is this appropriate? The original tile has been installed for approximately 6 months.
Replies
Tile over tile.
Tile over tile is acceptable under certain circumstances. If the original tile was installed properly, if extra thickness won't matter, if transitions will work, and with the right adhesive. There are kinds of thinset that are approved by the manufacturer for tile over tile. Under certain circumstances epoxy thinset is called for. Since yours is a shower floor be sure that the tile around the drain works out to your satisfaction.
Yeah, I've seen this done fairly well in commercial situations. The drain is the tricky part -- if the drain can't be raised (some can) then there will have to be a fillet of some sort around the opening, and the drain grate will be depressed significantly.
Sometimes it works, sometimes it doesn't. For sure I wouldn't let anyone do it in my house.