Depends. If all the sites you post it on are relevant to your music, then it shouldn't hurt. On the flip side, the only reason I would put it on one site is if I had some sort of exclusive agreement with a website, distributor or blog...
I noticed you asked about A/B (split) testing in another thread earlier. Great way to start testing... Post it on multiple sites, see which perform better... Then in the future, if they all cost you $10 each, for sponsorship:
One website got you 100 downloads/sign ups (whatever you are using to quantify it's success). The other got you 5.
There's a clear winner between the two. You now know which one to use and which one not to...
Cheers,
Jordan