When looking at my profile in other sites I noticed that my reputation score had an extra ten reputation to what my profile here says. Why does this occur and is there a way to fix it? I also looked at it when logged out and still had the same issue. The other accounts also display fine here.
The accounts are stored in a denormalized place on our network, meaning they're a slightly outdated copy at times. In addition to this by-nature lag, there were cases where updates just didn't happen reliably. A few months ago we put in a system that will notice these discrepancies and fix the denormalized store so the issue corrects itself on-view.
You shouldn't see these types of differences anymore, if you do they'll be gone within 10 minutes (the cache duration).
You actually have multiple accounts for each site within the stack exchange network, and each one has it's own reputation score.
The accounts are linked though, and you get a small reputation bonus for linking your account, so you start higher.
You also have a network account which you can link to on your user page.