I have 3 sphynx and my bond with all three is very strong, each in their own way. They love to cuddle and hang in my hoody.
When I added number 3 (got my boys together) my boys were a little less cuddly with me the first 2-3 weeks. Guess they had to get used to the new situation. But now my bond with them is back to how it was.
And I so love watching them play together, to see the playfights, see them having fun and melt when they cuddle together!
So I wouldn't worry too much. I think adding a second sphynx will mean double love and double fun for you.