New Colony Six unknown? oddity

What's up with the stock numbers? Neither look like Sentar's numbering series - and the A-side and B-side have different prefixes/suffixes.

As the name was changed from Sentaur to Sentar after "I Lie Awake" and before "Cadillac", it would have been sometime between April and August '66. Maybe a withdrawn release featuring "The Time Of The Year Is Sunset" instead of "Cadillac" as the A-side, paired with "Sunshine"?
 
This was a deleted release.
I have never seen it before.
It came out in June, 1966.
One side was cut at Stereo Sound Studios, the other at Ter-Mar, hence the different prefixes.