I don't believe this is a bleach and redevelop toner, but a single solution one. Is this similar to Kodak brown toner? I use the Freestyle brand of brown toner.

I have not tried it with Adox MCC 110, however. I love it with Ilford MGWT FB (which responds rapidly and intensely, very easy to over tone.)

I HAVE used brown toner with Freestyle's Private Reserve RC, which I and most people believe to be re-branded MCP, 312 (pearl) in my case. It works fine, but gives, naturally enough, a considerably cooler brown than the rich warm ones of the MGWT, and takes a LOT longer. But I didn't dual tone with selenium and I didn't use sulfite so I really can't answer the question here. However, if the fiber based MCC 110 (I do use that paper and like it a lot, just haven't tried brown toning it) responds to Viardon anything like the MCP 312 responds to Legacy Pro (aka Kodak formula) brown toner, any kind of "stop bath" for the toner is totally un-needed. I toned for 10 full minutes in full strength toner to get a good result. Toning is quite slow so I think a water rinse should do fine.

But I realize that's an awfully lot of "buts" - if a different (but similar) paper responds to a different (and maybe similar) toner in a similar way, after toning with selenium... Not much help I'm afraid.