We have a group of "investors" I guess you can call it, we share masternodes that individually we would not be able to afford/risk. Works out fairly well for everyone 
Coins such as vivo with masternodes costing 1-2btc, means entry is very expensive, So they actually have a few groups that do this.
Last I recall there was something like 20-30 shared masternodes.
Sometimes members do take their share out to make their own nodes once they have accumulated enough
To answer OP:
Alot of coins can have multiple masternodes on a single server. depends if they can share ports/IP's.
Best thing to do is join their communities and ask them
Coins such as vivo with masternodes costing 1-2btc, means entry is very expensive, So they actually have a few groups that do this.
Last I recall there was something like 20-30 shared masternodes.
Sometimes members do take their share out to make their own nodes once they have accumulated enough
To answer OP:
Alot of coins can have multiple masternodes on a single server. depends if they can share ports/IP's.
Best thing to do is join their communities and ask them