I have allowed the security deposit or deposits to be spread over an acceptable time compared to their rent.A unit I have is in an HOA that requires a security deposit equal to 1 month's rent, then I charge 1st month's rent, and my security deposit for the inside of the unit.It is not that uncommon these days depending on total amount requested that they may not have all the funds.

However, it is not uncommon for investors to buy a leasehold property as an investment - obviously the numbers need to work for them to recapture their initial investment as well as offer a satisfactory ROI.  

I suspect they are using someone else's identity or hiding something negative from their landlord.It is not uncommon for people to have good credit but still have an eviction or other problems with a previous landlord.

@Ralph Hunter I have seen those concrete ones and I love them, but I'm not entirely sure if tenants would like them since they are uncommon in my area.

It is not uncommon that some properties don't CF until 5 years down the road. 

If they have un-common names you may get lucky. 

@Tim Bee it's not uncommon in a property management agreement for the management company to keep late fees or to split them.

this is not at all uncommon. 

But also the uncommon expenses that you may overlook, such as auto mileage, BP membership, etc.

It's called  "Uncommon Entrepreneurs".