title: You cannot specify the same gem twice with different version requirements
body: <p>I have 2 plugins installed(redmine_backlogs and redmine_ldap_sync), but after upgrade of redmine_ldap_sync from 2.0.0 to 2.0.1 a Gemfile was added.</p>
  
  <p>Here the backlogs's Gemfile <a href="https://github.com/backlogs/redmine_backlogs/blob/v1.0.2/Gemfile" rel="noreferrer">https://github.com/backlogs/redmine_backlogs/blob/v1.0.2/Gemfile</a>
  and ldap sync's Gemfile <a href="https://github.com/thorin/redmine_ldap_sync/blob/2.0.1/Gemfile" rel="noreferrer">https://github.com/thorin/redmine_ldap_sync/blob/2.0.1/Gemfile</a></p>
  
  <p>In both cases, the <strong>simplecov</strong> is in the test group. I tried to run</p>
  
  <pre><code>bundle install --without development test
  </code></pre>
  
  <p>but I got this error:</p>
  
  <pre><code>You cannot specify the same gem twice with different version requirements. 
  You specified: simplecov (&gt;= 0) and simplecov (~&gt; 0.6)
  </code></pre>
  
  <p>This does not seem to make sense. Is there a way to bypass it without editing the file?</p>
  
  <p>Thanks</p>