Any way to avoid duplicate domain while making backlinks

Hi all,

I have a small team for linkbuilding by which I do provide various type of linkbuilding service to my clients. But the problem is that few of clients order again and again for their same domain but it is tough for me to track all of his previous order and avoid the domain where I or my team already created a links.

So, I am trying to find a way to avoid the pages where my team or I already posted a link. Is there any soft that can help me out. Please keep in mind that I cannot do this manually as it will take a long time to track client's all the order and send it my team to avoid those domain.

Thanks in advance,