Characters inspired Two And A Half Men?

I was watching this gem of a film for the first time in years the other day, and it occurred to me that there are similarities between the two main male characters - Brad and Jonathan - and brothers Charlie and Alan Harper in Two And A Half Men. Leaving aside the obvious physical resemblance between the two pairs, there are also similarities in character and occupation:

* Brad is a songwriter, often seen at a piano; Charlie Harper is a jingle writer, and also often plays the piano.
* Brad is a charming but conniving lothario; Charlie Harper is also a (less charming) conniving lothario.
* Jonathan is a constantly complaining, rather weak-willed divorcee (and possibly repressed homosexual?); Alan
Harper is divorced, weak and self-pitying, and although apparently straight frequently behaves in a way that
leads Charlie to question his sexual orientation. Both Alan and Jonathan also frequently indulge in schadenfreude.

Am I right?