You could use regex to change the ee to another single character. If you think @ does not occur in the data,
words(regex("Test1eeTest2eeTest3eeTest4","ee","@",GLOBALREPLACE),"@")
{"Test1", "Test2", "Test3", "Test4"}
If you are not sure about @ but are pretty sure the ASCII Unit Separator character does not occur, you could use
words(regex("Test1eeTest2","ee","\!U001F",GLOBALREPLACE),"\!U001F")
The Unit Separator is unlikely to be in your data:
the US is really a single character in spite of appearances. Your font may show it differently, or not at all.
Craige