I couldn't find any mention of Tottenham also being interested in Mbeumo, I see that only Manchester United are negotiating for him and it looks like they will come to an agreement for €70 million. Manchester United have already paid €73 million for Cunha, they want to strengthen their attack. But what about the defense, they need a stronger goalkeeper and a couple of reliable defenders wouldn't hurt either.
Tottenham have not been active in the market so far maybe later in the window they will make some signings now that they have settled their search for a manager. For the time only Manchester United are legit contenders for the signing of Mbeumo this summer and only United have submitted formal bids for the player. I think Mbeumo is going to be a hard sell because the price tag Brentford put on him is very high. So far Brentford have rejected two offers from Manchester United.