Sara,

please keep to the thread, PM is not for answering questions

from your PM

I'm really getting confused, I've been working on this for eight hours now and I'm still at stage 1 and I'm sorry that I don't ask the questions, but I simply sometimes don't know when you ask a question or not. I've been busy with this for a few hours and I'm getting really messed up in my head over how to solve this
You need to approach this logically and a step at a time. Focus on how you would go about identifying a correct match, not an incorrect one

To summarise:

in order to be able to match correctly, from what you have provided, it looks like you need a number of algorithms. so far you have provided one answer, - that it is sometimes preceded with an underscore. Solution has been provided for this answer (post #13) but you have not provided any feedback as to whether this solved the problem, partially solved it or anything. So:

question - how may false matches were you getting before applying the solution?
question - how many false matches do you get after applying the solution?
question - how do you know it is a correct match?
question - how do you know it is an incorrect match?
question - is there any other pattern that helps identify a correct match (like the preceding underscore already provided)?
question - if not, if you are inspecting the data manually, how do you decide what is a correct match or not a correct match?