An undergraduate degree, a masters, and a PhD is completely normal for an academic. The latter two are often picked up while on a studentship with a stipend. Although it is possible to self-fund graduate school it's normally not a great idea.

The second masters could have been a false-start at an academic career (change discipline/university part way through study and exit with an MA), a holdover from a pre-academic career, or just done for interest.

I've got a BA in politics, a PGDip (2/3 of an MA) in local government management, an MSc in Internet social sciences and a DPhil. I currently work as an academic. I paid only for the BA and the MSc, and under slightly different circumstances wouldn't have needed to pay for the latter. It's not uncommon.