Comment by Kevin Walsh1:
Apparently track A2 is an alternate take. This was posted on the official Dusty Facebook page on 9 November 2023:
“Having celebrated the anniversary of I Only Want To Be With You yesterday, I thought there may be some fans who had never heard the alternate take of the song. It first made an appearance on a re-release of Dusty's Greatest Hits album in 1983. It was a mistake apparently and it would seem that Dusty was not too happy about it, that said it's still great to listen to a slightly different take.”