What steps will reproduce the problem?
1.$ winetricks dotnet30sp1 (installs 2.0SP1 & 3.0SP1)
2.$ winetricks dotnet35

What is the expected output? What do you see instead?
I expect the dotnet35 installer to run, but instead I get 

Executing w_do_call dotnet35
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error: dotnet35 conflicts with dotnet20, which is already installed.
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What version of the product are you using? On what operating system?

$ wine --version : wine-1.7.34
$ winetricks --version : 20150114 - sha1sum: 
1a5b4e1a76fc7c599d9984bff04d69b01115b2f9


Please provide any additional information below.

I tested with a clean install of 32 bit Ubuntu 14.10.