Between two stools is a fall.
More Manx Proverbs:
A short courtship is the best courtship.
Manx
Many a man has been guarding the bush and another plucking the fruit.
Manx
The crooked bannock straightens the body.
Manx
A rich man without liberality is like a tree without fruit.
Manx
Maybe the last dog is catching the hare.
Manx