I believe I finally solved this with my two PayPal accounts; not sure, as I've not used either one recently, which I ought to have tried before posting this.
I have two Bluehost accounts for someone whose web site I'm creating, one to get to the site editor, the other to get to his e-mail account. To do that requires that I have two PWM entries, as the log-ons are different. Both log-on setups work with PWM, but I've found that, at least when I'm logged on to the e-mail account, that PWM keeps showing the pop-up box for selecting which log-on to use, which is a nuisance that I've not figured out how to solve.
Suggestions as to how I might fix this are welcome (except those that tell me to go away...).