How many 2nd home mortgages can you take?

[Mason Blake]

I have it in my head, probably from listening to many many REI podcasts, primarily BP, that one can only take out a single 2nd home mortgage at a time. If you wanted to do an additional 2nd home mortgage, you'd have to pay off the first or do something creative to "release" said mortgage product.

Do I recall incorrectly? My mortgage broker tells me that there is no limit, but this doesn't seem right.