yes, this is the intended way with all mikrotik platforms. that support both POE-in and DC power in. even the smallest ones. it will prefer the one with higher voltage. so whenever the preferred one's voltage drops to zero, it will use the other one w/o any hassle.

there is however a different method, that would require you to grab a soldering iron and install two screw terminals onto the board.
in the empty part of the case you can then put two PSUs of your choice (we use meanwell ones) and you can install proper IEC C14 receptacles onto the back of the housing. there is already a cutout there that accepts readily available terminals. i can post some photos if you wish.