At this stage of the hobby, where there have been so many boards released with a multitude of creative case designs, it is likely that different designs could come to the same decision that certain designs would be cool to try as pointed out by Mul7i and ClickClack above.
In the same vein, it is also likely that the same name of the board could be chosen like for the:
1) Arc (ergo keyboard from yz) and the Arc60 (sold through ClickClack)
2) Navi (70% board from Matrix) and Navi60 (from psychetype)
3) PhaseOne (65% board by OpenKey Design) and PhaseOne (75% board from PhaseByte)
Nothing wrong with having the same name or similar design ideas (as long as it isn't outright copying), it can just happen at this stage of the hobby.