Since the results of this merge are extremely dependent on the values of the IPAC variable in both data sets we cannot tell with the data and what your expectations actually are.
What makes you think that you are "not getting the right number for match and un-match.".
As in example data values, not some "the numbers aren't right" statement.
Provide an example of IPAC values that appear in the matched data that shouldn't and values of IPAC that should not appear in the matched.
Some common issues generally related to the BY variable not being exactly the same value in both sets.
If IPAC is numeric then there may be a decimal portion that you don't see that has values that might appear identical that are not. The fix if this is the case is to round the variables in both sets before merging to a standard number of decimal places.
For character variables the BY is going to be case sensitive, "ABC" does not match "Abc". The fix here is make sure the case is the same in both data sets, use any of UPCASE, LOWCASE or PROPCASE functions on the variable in both sets.
Sometimes you may have a leading space(or multiples) and " ABC" does not match "ABC". Trailing spaces won't have any impact on the comparison but leading spaces does. The fix may be as simple as using the LEFT function on both datasets. If the "space" is actually a different non-printable character this may get more complicated.
If the format for the IPAC variable is shorter than the length you may see "ABC" (format $3.) when the value is actually "ABCDEF" (length 6 or more). This would likely require either changing the values of the variable or possibly creating a separate variable in each set to have identical values to merge on.
