Could adding no. of threads in RedisMqServer result in duplicacy of processing of the same message?

Question

We have implemented the ServiceStack.Redis library's RedisMqServer in the following manner:

RedisMqServer _mqServer = new RedisMqServer(_redisManager, retryCount: 2);
_mqServer.RegisterHandler<T>(base.ExecuteMessage, 4);
_mqServer.Start();

Where 4 is the no. of threads.

So my question is could this result in duplicacy of processing any messages?

I expect this code to process thousands of requests with no. of threads as 4 without resulting in duplicate processing of any message.

So does this library ensures this automatically or do I need to check for it explicitly? If yes, then how?