Perform An Action On Each Record In A Table In Turn

OK, usually I can figure these things out for myself, but I'm realy stuck on this one and any help would be appreciated

background: I work in a small scale pilot production line, and we take a series of measurements for every part that we make, each of which has a unique ID. Sometimes we need to take the measurements more than once, so that the data output from the measurement system (which it can append straight to an access table) has a part ID and a measurement number, the combination of which is unique (for reasons that I won't go into it is not possible to combine them into a single field, otherwise we would do this)

problem: The measurement system can be temperamental and sometimes sends the same record more than once, and It is horribly time consuming to go through and check manually
It occured to me that we could send the measurements to table1 (where they would be stored temporarily), and write a sub to go through each record in table1 in turn, compare the part ID and measurement number to the records stored in table2 (where they would be stored permanently), and append the record to table2 only if the part ID and measurement number combo has not already been taken, before moving onto the next record in table1 and doing the same thing

The part I just can't figure out is how to go through the records in turn and compare them, I can do the append and deletion using SQL, that's not a problem.

if anyone can point in the right direction I'd be realy grateful (or tell me if I'm barking up the wrong tree completely)

regards
Bogzla