You can get fruit trees where two different types have been grafted onto the same rootstock, a photo would be a big help.

Cherries and apples wouldn't be compatible that way, MG, though apples and crabapples would be.

I have Googled cherry apple and it seems that the said tree comes from the far east. The fruit looks like a cherry but when it shows a fruit which has been cut open there are seeds in the centre rather than a stone which would lead me to believe it is a species of malus or what we would call a crab apple.

Sounds about right to me Jimmy

I just searched it myself. It's apparently an ancient group of heirloom apples from China, at the eastern end of the Himalayas.