Problem with external lookups

I have a problem that I've been fighting.  I feel like I'm missing a very simple step but don't know what it is...So, here goes.

I have a model that is pulling in 2 external lookups.  Both are working fine.  However, they pull the same kind of data and I ultimately need to combine the results into one column.  There is no situation where the lookups will pull data into both lookups - its either one or the other but I ultimately need one column.

I've tried to change the fields to numeric and use formulas to pull them together.  I've tried to make them character and use formulas to pull them together.  Nothing seems to work.  I can get an "if" formula to pull in one or the other but not both.

Example"

Field 1      Field 2    Requested results

3788                        3788

95743                      95743

                 12345     12345

etc.

Help?

Thanks for all your ideas!

Kathi