I assume you are referring to clan silver tags, in reference to your clan members having your clan silver tag and another clan's silver tag on their friends list simultaneously? If I am wrong, I apologize. However, I do not see the harm in this, as the silver tags are NOT official clan lists and are only used to aid in communication. All the clans in my section are full of people who used to all be in the same clan, and by adding these silver clan tags, they are able to keep in touch with their entire section more easily. Besides, we really cannot regulate who people befriend on their Xbox live gamer tags.
-Ashley