Hi sheepdip1234, I'll take a (hopefully educated) guess that the tambourine was added when the mono single was being mixed, and presumably the other (stereo?) version is taken from the multitrack and so is missing the overdub. This has happened elsewhere.
Seems a good place to add a DC 5 comment. It appears that there are 2 versions of "Bits & Pieces" around. The original version has a prominent tambourine in it. The 2nd version (which I have on a 6 album EMI set entitled "100 Greatest All-Time Hits", has no tambourine anywhere.
I'm equally thankful you added the images, as I haven't got a cover for my copy! (It was a loose disc in amongst a joblot I got a while back). I THINK my labels are slightly different though... I will check when I'm back among my vinyl.
Images added for this album. Thanks to nboldock for submitting this record. It is the only DC5 record that I still have in my collection because it is in good stereo. All that Mr. Clark sent over here to sell in the US was mono and poorly re-channeled fake stereo. When I found out about this album, I bought it as an import.