Can we have more then one onmouseover and onmouseout in the single HTML statement?

Question

Let me explain my problem -
Lot of code in the QueryHome is generated by a single file and changing it is very risky. Using one of the operation we are generating the code which is adding onmouseout and onmouseover.
Now we want in a specific case where we want to add a special onmouseover on top of which is generated in the code. Now the question is it valid to have more then one onmouseover/onmouseout.