Matt, this is one of a host of WordPress issues that will make you want to dig into phpMyAdmin and monkey with the database tables.
Odd numbering, multiple draft copies and autosaves, etc. bloat and clog the system, and as you noted, may impact SEO.
Manually trimming the fat can go a long way
um, to be responsible, I'll say be careful:
"Manually trimming the fat the wrong way can go a long way towards killing a site"
