Can I write this in an expression or is there a better way in custom code?

Let me know if you need additional clarity to my question!

Current: This works as needed.

=Right(Fields!REASONB.Value,Len(Fields!REASONB.Value) - InStrRev(Fields!REASONB.Value,"-"))

This expression removes all characters from first instance of  '-', located from the right end of string, to the beginning of the string.

Example:

When expression runs on data below

ReasonB
SMPLT - QSY - Error 1234

Returns

ReasonB
Error 1234
----------------------------------------------------------------------------------------------------------------------------
Desired:

In addition to the above expression I would like to COMPARE Fields!REASONB.Value with Fields!REASONA.Value

For an example:

If Fields!REASONB = Fields!REASONA Make ReasonB column blank.

ReasonA                                                 ReasonB
SMPLT - QSY - Error 1234                               SMPLT - QSY - Error 1234

Returns

ReasonA                                                 ReasonB
SMPLT - QSY - Error 1234                              

OR

If Fields!REASONB <> Fields!REASONA Return Maintain what is already in Fields!REASONB

ReasonA                                                 ReasonB
SMPLT - QSY - Error 1234                               Flooding

Returns

ReasonA                                                 ReasonB
SMPLT - QSY - Error 1234                               Flooding