Hello,
The SAP Help Link shows that you can have multiple enhancement implementations indirectly tied to an Enahncement spot. It does not show an enhancement point hacing multiple implementations.
An enhancement spot can have many enhancement points and each enhancement point ( enhancement definiton) - especially in the case of a source code enhancement can have only one enhancement Implementation assigned. Thats the limatation of the Enhancement option ( Source code Plugin ) and it makes sense. There cannot be multiple Source code enhancements for one poiint, if so how do you determine which plugin to pick at runtime?.
However,In the case of source code plugin's, I am not sure if we can reassign an Enhancement point to multiple enhancement spots. I have never tried that.
Enhancement option like BADI's allow to have multiple Implementaions tied to one definition, because they provide us a mechanism to choose the right one ( Filters )..
Hope this Helps. Do correct me if I am missing anything.
Venkat.