Any disadvantage to multiple applications?
I don't think there is anything wrong with this, as long as on the 2nd application a year later, it is made clear that something changed in the year prior. This could be additional courses taken, higher test scores (GRE for example), etc. I think if your application is legitimately improved over the year, no one would ever have a problem with this, but a potential reviewer might be annoyed if they receive the same application year after year without notable changes/improvements.