checking out multiple branches of a project

[Chris Cheshire]

I have a project in source control called mylib (for example) that 
contains libraries used for my various programs. Currently I need to 
make some changes to a development branch, as well as some changes to 
the head. I have been deleting one, checking out the other, deleting it, 
checking out the original one again constantly, and it is starting to 
get annoying. Is there any way I can check it out so that the structure 
looks something like :

~/src/mylib/HEAD/...
~/src/mylib/dev-branch/...

Or can I only have one branch checked out at a time into a given "home 
directory", making it be something like

~/src/mylib/...
~/src-dev-branch/mylib/...

Thanks

Chris