There could be several reasons why.
Property managers will be looking at the following:
1) Rental history (no evictions or collections)
2) Credit (no collections on a utility bill....)
3) Background check
4) Income (should be 2.5-3 times the rent)
As an agent who helps about 200 people a year find rentals in Las Vegas, I personally don't want to deal with people who stack up applications.
It should be first come, first serve which is how most places operate out here.
Otherwise, what is to stop the property manager from collecting multiple application fees?
I would try to find out why you were denied.
It could be that there is something you are not aware of on your credit / background or it could be for reasons they just aren't telling you.
Either way, it's worth finding out.
Wynn Realty Group