While there may not be a clause in your employment contract there may certainly be a clause in the contract between your employer and the client that could possibly be more hassle than it's worth for the client.
The only way to know is to go through the process with the client, declare the possible conflict early on and let them research it on their side to see if it's worth going through with. Best of luck.
The only way to know is to go through the process with the client, declare the possible conflict early on and let them research it on their side to see if it's worth going through with. Best of luck.