It seems that the History Editor shows only every second price when I open .t1 file in it. Also when I compare the number of records it shows with the number of lines in the original .csv file it's only a half.

(If it is on purpose it would be probably good to mention it somewhere)

I can not fix the History Editor as it was donated by a user, but you can alternatively convert a history file with the "CSVfromHistory" script and display it directly in an editor or in Excel.

Yeah, I don't mind. It just made me confused for a while when checking my exported prices against it so I thought it's worth noting.