Help something really strange is happening

-- HikaShop version -- : 2.3.0
-- Joomla version -- : 2.5.20
-- PHP version -- : 5.3.29

When I set up the shop, I used my husband;s email as one of the test users for the site, before it was even live.
The shop has been running for a while now and everything is okay, except that recently two orders came through that were sent to my husbands email address, but with different billing addresses and payapl payment that went through not from our account.

How can that be? The users don't have to register, they can just shop, is that maybe when it picks up my husband's email address?

So to clarifiy, the orders look as if they were coming from my husband, but they actually come from completely unrelated people.

Any ideas?

Thanks
Anni