Fix comparison in dup resources acceptance test

Due to changes in Puppet 3.6.0, the comparison done in our resource duplication
tests no longer matches the actual output. This patch ammends the comparison to
match Puppet 3.6.0 output now.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #968 from kbarber/ticket/1.6.x/fix-puppet-collection-collision-test

Fix comparison in dup resources acceptance test