Split multiple data scans into separate colum

Hello,

I'd like to split my data from two columns into multiple columns in order to do averaging.
My data looks like this:
Mass| Intensity
XX | YY
XX | YY
...
Mass|Intensity
XX2 | YY2
XX2 | YY2

This repeats for an X number of scans depending on the run. The mass values are the same through out so if it is possible to somehow move the intensities into rows following the mass that would be great. There are 6000 mass points per scan.
I usually use a separate data application that I don't have access to at the moment and was hoping someone can lead me in the right direction with Excel.

Thanks in advance.