Objective Tree: "Target Completion" sometimes appears duplicated

Issue Summary

This is reproducible on Data Center: (yes) 

In the old view when in list view mode, when selecting the "Columns Shown" section  the "Target Completion" option appears twice

Steps to Reproduce

1. Set a portfolio for T1
2. In the left menu, access the Objective Tree page
3. Click on "Portfolio Objectives" and then click on the "List View" button
4. Select the column "Target Completion" and then click on save
5. Click on the "columns Shown" and notice that the "Target Completion" may be appearing twice (is an intermittent problem)

Expected Results

"columns Shown" section only one option for the "Target completion"

Actual Results

As per our tests, In some instances, it displays the "Target completion" twice

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available