Design considerations when combining multiple DC DC converter with the same input, but different output
Typical designs with multiple switching converters either use a common clock for the switching frequency (but with phase offsets for each converter), or different switching frequencies that ideally aren't multiples of each other, to minimize the chance that both FETs turn on at the same time.
When you do that, you need less total capacitance on the input side, so they can probably share the 10uF, but I'd leave the 100nF in place on each leg, since that is what filters higher-frequency noise.
For unsynchronized converters with the same frequency, I'd leave the capacitors in place, and possibly even add a small inductor on each leg to improve the filtering.