Any Systems Administrator can now merge duplicative labels. To merge labels, go to your Organization Settings and then click on the Labels tab. Here, you can review all the labels in your account.
First, select the labels you want to merge:
Next, click on the Merge button:
Then, select the label to become the master label and click Merge:
Note: When you merge labels, all content that had the separate labels applied to them will be combined under the new, merged label (or the "Master Label").