[Haskell-cafe] Problem with cabal-install where package requires* mutually exclusive versions of another package

[Mark Wassell]

I am trying install a package using cabal-install however the package 
requies an older version of QuickCheck and one of the required packages 
requires the latest version:

$ cabal fetch Reactive

Resolving dependencies...
cabal.exe: cannot configure Stream-0.3.1. It requires QuickCheck >=2.0
For the dependency on QuickCheck >=2.0 there are these packages:
QuickCheck-2.1 and QuickCheck-2.1.0.1. However none of them are available.
QuickCheck-2.1 was excluded because checkers-0.1.3 requires QuickCheck <2.0
QuickCheck-2.1 was excluded because reactive-0.10.5 requires QuickCheck <2.0
QuickCheck-2.1.0.1 was excluded because checkers-0.1.3 requires QuickCheck
<2.0
QuickCheck-2.1.0.1 was excluded because reactive-0.10.5 requires QuickCheck
<2.0

How can I get around this? I could work around this and install the 
packages individually. Can I have two versions of a package installed 
(ie QuickCheck) and will everything get resolved correctly?

Mark