Is There A Stamp That Exists Only As CTO (Canceled To Order)?

Is there any stamp (valid for postage when issued) that was NEVER available in mint condition, and was NEVER postmarked in the mailstream because it did not circulate?

Is there a stamp that exists only as CTO (canceled to order)?

Maybe some "Sand Dune" stamps?

Somebody said that there are some GDR overprint stamps available only as CTO, and they were sold by GDR for hard currency.

I see now a related thread:
https://goscf.com/t/74458&whichpage=1

Somebody asked how many fish stamp designs are only available as CTO, from the 10,000 stamps checklist of ATA.

I know at least one instance os such stamp.

In 1978, Bulgaria issued a set of stamps commemorating the Philaserdica'79 stamp exhibition.
Next year, the set was re-issued in changed colours. It differed in the issue year on the stamps, as well - 1979 instead of 1978.

It was a usual practice in Bulgaria at that time that all newly released stamps were partially CTOs. So was the case with the said set, nothing unusual.

However, several years later, in 1983, they received supposedly an order from the USSR (the main market for the Bulgarian CTO stamps then) for the re-issued set in the CTO state. No stamps were available, so they found "an easy way out" - printed an additional run as CTO.
Not that usual, yet, it's not the case the topick starter asked about, as the set was available as mint when released.

But...
The 35 stotinki stamp in the re-issued CTO set was unusual - it had the issue year of 1978 but the colours of 1979. This stamp never existed as mint.

Here are all three in the order as tthey were issued:

Thank you!

The stamp issued below is only "officially" issued by the Cocos Is. PO as a CTO. I am aware that MNH examples exist, however they aren't kosher or legal and I haven't seen one offered in quite some time. Likewise, I am not aware of official covers used by the govt of Cocos but they may certainly exist.

It's the only used stamp in my collection.

Thank you, shermae!