How to Use GFCI Square Cover?
I just had to deal with that last week.  On an expensive rundown timer, no less!    The rectangle shape is Decora, and those outer screws hold Decora plate covers, which use an extreme outer position.   You have two choices: 


bend or hacksaw them off.  Your device can never be used with a normal Decora cover plate.
dump the accursed raised cover (you certainly don't need the cubic inches) and go with a 1-gang mud ring for a 4" box.  This is flush, but has a 1/2" extrusion the size of a 1-gang box.  This has the space needed.     And then you use a plain Decora cover plate, which needs those threaded holes.  If you need dual Decora, they make 2-gang mud rings too. 



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