sure
Or
1 250w for a dollar or two more.
and keep the 100w in a fish(stuff) box, for a back-up or the next tank. Whichever comes first.
Or(the "depends" stuff)
do you require a back-up for everything in your tank? ie run two filters, two heaters, etc.
do you want to run two smaller heaters because of the "malfunction" possibility. So the malfunctioning heater doesn't boil your fish, while your away?
Then sure, go with two smaller heaters.