Switching from Propecia to Proscar

[win200]

I've been on Propecia (branded, not generic) for eight months, and I'd love to switch to Proscar to get the cost down. If I'm moving from branded Propecia to branded Proscar, can I just immediately stop taking the Propecia and start taking one-fifth of the Proscar? I thought I read at one point that people were experiencing sheds from moving from one medication to the other, but maybe that was between generics. I mean, aren't Propecia and Proscar supposed to be pharmacologically equivalent?

Thanks for any feedback.