[Haskell-beginners] latest Haskell Platform build fails

Hello all,

I am trying to install the latest version of Haskell Platform and am 
having a problem.

I created a new VM and installed Ubuntu 14.04 server and applied the 
latest updates. Also installed packages
"build-essential" and "zlib1g-dev".

I then downloaded and installed ghc-7.8.3 from 
https://www.haskell.org/ghc/download_ghc_7_8_3#x86_64linux
and then downloaded and installed cabal 1.20.0.3 from 
http://hackage.haskell.org/package/cabal-install.

After installing cabal, I did a "cabal update" followed by "cabal 
install hscolour".

Then downloaded the latest Haskell Platform tarball 
(haskell-platform-2014.2.0.0-srcdist.tar.gz) and attempted to
install like this:

./platform.sh ../ghc-7.8.3-x86_64-unknown-linux-deb7.tar.bz2

This fails like this:

***
*** Building hptool
***
Building hptool-0.1...
Preprocessing executable 'hptool' for hptool-0.1...
***
*** Running hptool
***
# rm (for 
build/.markers/rel/build/target/usr/local/haskell/ghc-7.8.3-x86_64/lib/happy-1.19.4)
# rm (for build/.markers/rel/build/package/happy-1.19.4/build)
happy-1.19.4 needs mtl-2.1.3.1
 >>> Building happy-1.19.4
# cp (for build/.markers/rel/build/package/happy-1.19.4/build)
# rm (for build/.markers/rel/build/package/happy-1.19.4/build)
# ghc-pkg (for build/.markers/rel/build/package/happy-1.19.4/build)
# ghc-pkg (for build/.markers/rel/build/package/happy-1.19.4/build)
Reading package info from "build/package/mtl-2.1.3.1/inplace.conf" ... done.
mtl-2.1.3.1: package(s) with this id already exist: mtl-2.1.3.1
Error when running Shake build system:
* build-all
* build-product
* build/product/haskell-platform-2014.2.0.0-unknown-posix-x86_64.tar.gz
* build/target
* 
build/.markers/rel/build/target/usr/local/haskell/ghc-7.8.3-x86_64/lib/happy-1.19.4
* build/.markers/rel/build/package/happy-1.19.4/build
Development.Shake.command, system command failed
Command: 
/home/mmartin/Downloads/haskell-platform-2014.2.0.0/build/ghc-bindist/local/bin/ghc-pkg 
register --package-db=build/package/happy-1.19.4/package.conf.d 
--verbose=1 build/package/mtl-2.1.3.1/inplace.conf
Exit code: 1
Stderr:
mtl-2.1.3.1: package(s) with this id already exist: mtl-2.1.3.1

Any suggestions on how to get past this?

Thanks,
Michael Martin