I hadn't seen these yet. Intriguing. To answer your question, no you cannot. If your using the VS3050 that pump wil do 160gpm at 50 feet of head. A 4" line can only handle 240 gallons per minute to be within minimum defensible code compliance. Obvisouly you want to be below that for a just in case factor. With two pumps on one line you would be exceeding that. Shoot for 4.5 feet per second through your pipe. Some states require a 1.5 feet per second flow rate through each drain outlet. It's not always about the cover. Hope that helps.

It is not a terribly great idea to tandem pumps off of one suction line. They have a tendency to fight each other. With a vacuum lock safety installed on each I suspect that they would constantly be shutting each other off.

I have use the color match covers on many projects and am very happy with them. As others have stated, it is not the best idea to tie the two pumps into one drain. Would be best to use two, one for each pump, still better than four.