I have the following line of code:
var dmrReceived = new DownloadMessagesReport();
StyleCop and ReSharper are suggesting I remove the redun
So your code is
var dmrReceived = new DownloadMessagesReport();
dmrReceived = dc.DownloadNewMessages(param, param2, param3);
The second line does not fill the object you created in the first line but it completely replaces that object. So the first assignment is not needed (as the first object is never used), which is what R# is warning about.