Two fuses is not THAT bad.. It do reduce the current abit, and with that, allso the quality of the audio.
The idea behind two fuses at in this case 25A, instead of one fuse at 50A. Is that it's easier to buy a 25A fuse at a gass station, than a 50A.
Well, a 50A fuse is not so hard to get at a gass station. But higher fuses is seldom, becaus they sell to little of them.
There is some that say that two fuses in series is better than one big fuse when it comes to stopping dangerous peak voltages.
Having two fuses at 25A equals a 50A fuse.
So the amp will do about 50A * 13.8V = 690W @ 100%
About 650W on a class-d and about 520W on a class-b amp