From what I've just read at xerces.apache.org , Xerces 2.X and Xerces 3.x have different API's and therefore you'll need to link with one OR the other.
And as you can see from xalan.apache.org:
"The Xalan-C/C++ 1.11 library requires the Xerces-C/C++ XML Parser 3.0 or newer, version 3.1.1 is preferred.", while Xalan 1.10 requires Xerces 2.7.0 (will probably work with 2.8.0).
So yes, you will need two different versions of Xalan libraries, unless you can resolve your dependencies to Xalan 1.11.0 only, in which case you can have only one installed Xalan and one Xerces.