Searching through a list of dictionaries with a condition.

[Mr_Keystrokes]

It's not overwriting, you are removing the last iteration before you add a new one. The pop method removes the last item of the list. You keep removing an item and adding an item (lines 31 + 32), so you end up with one item. Remove line 31 and it should work.

You can also remove line 25. The with statement on line 21 takes care of that.

On the contrary, by removing the pop method it still returns the last sample ID, the only difference is that it's repeated by the number of key-values there are in the dictionary i.e.
S01933-11 r480
S01933-11 r480
S01933-11 r480
S01933-11 r480
S01933-11 r480
S01933-11 r480
S01933-11 r480
S01933-11 r480
S01933-11 r480