I found a way to avoid that a user has more then 1 account in the BOINC total stats. It involves some user interaction, and some programming on my part (half way already).

What the user has to do is create an account on the BOINCstats main page (sorry, can't use the forum user database) fill out a simple form, but to avoid account stealing, you have to post a message in the forums of all projects you participate in so I can verify you own the account. This is the only way to do this; I don't have your email address or your project sign-up code to check.
After doing this, all BOINC accounts will be merged into the highest ranking account, and from that moment on I'll guarantee that you have no more duplicate accounts. (Until another project is available, but this will then be added to your account as well).

Please let me know by using the poll if this is OK for you, or too much hassle.

But even if it's not done this way, the stats will merge sooner or later anyway, won't they?
Right now the problem was that predictor is running an older BOINC than the others, so the problem will solve it self soon enough for me. :-)

They will merge after some time....... and split up again when a new project is launched or when you upgrade to a new (major) BOINC version.

Actually, it may or may not split when you join a new project. If the new project assigns a CPID that is lower than the current CPID, it will not split for very long, as the new project will get the old CPID sent back to it. Since you are connecting to the new project, you can expect the split to be the length of your queue or less.

Upgrading to a new version will not in itself generate a new CPID, but if there is a major version change happening, and during the major verison change you join a new project that happens to generate a new CPID with a larger value than your current CPID, you will maintain the split longer.

The other way a split would be maintained for a long time is if a project were down for an extended period of time. e.g. S@H last month.

[EDIT] I just voted. None of the categories quite matches what I wanted to vote. I voted no. I do care about the split, but not enough to do much of anything because I expect them to be merged again sooner or later. Usually sooner.

And that sums up my opinion rather well too. I do care, but not a great deal, and mostly I don't care since I hope that most of the time, the problem will be small.
Major releases are scarce, but new projects could become a problem, I don't know. For now however, I don't mind waiting to see what happens.

I'm also in the group of people who care, but not enough to do anything about it...

Personally, I think that spending any energy on it at this point might be a waste of effort. The client is still maturing, and I think it is pretty clear that this will have to change on the BOINC end before we really can have a feasable cross-project tally going. Besides, this solution works well for a few of us but is not really viable when this site really gets cranking... personal verification is not a quality long-term solution.

Will stats from Predictor merge with my stats for other projects once Predictor moves to core client 4.x?

If you signed up with the same email address (case sensitive), and you have some machine running Predictor as well as one of the unified projects, then they should merge within a few days of Predictor comming back up.

Looks like the merge of dupe accounts has started to happen now that Predictor is coming back on-line. My second listing is now gone!