I'm not sure this qualifies as frequently asked, but I'm going to ask anyway;
It appears these days that the announcement of a new single is enough for many to scuttle off to iTunes to download whatever version of the track they can find.
There are instances where the single release includes a featured artist that the album track doesn't, so we have occasions where a track is chart listed with a featured artist before it's even available. A recent example that springs to mind is
Worry About You by
Tyler James featuring Kano, which was released on 15th February, so could only, really, possibly have charted w/e 23rd February. However, it entered the chart w/e 09 February at #183 and climbed to #52 the following week, from what could only have been sales of the track from
Tyler James' album,
A Place I Go, which does not feature
Kano and is more than half a minute shorter in duration.
Now, I can accept multiple variants on a track being combined into one for sales purposes (albeit I believe sales of an EP or Remixes bundle should only count as one sale, equivalent to an old fashioned multi-track CD Single - remember them?), but surely tracks should be correctly listed on the official charts, even if the catalogue number used is the same?
To my mind, at least,
09 Feb #183 Tyler James - Worry About You
16 Feb #052 Tyler James - Worry About You
23 Feb #055 Tyler James ft Kano - Worry About You
02 Mar #038 Tyler James ft Kano - Worry About You
is correct. What would happen if, under the existing system, after the second week the track dropped out of the chart?
Kano would forever be credited with an appearance in the chart for a track which he didn't appear on!