Datestamp Errors

I share a couple of unusual covers, in that both have errors in the date format.

The one on the left is from Qatar, while the one on the right is from Bahrain.

This error is easily explained, in that the hammer used had 'slugs' for the date, which would have to be changed in a daily basis to make up the correct date (today its a simple tumbler). so the order of the numbers and letters could easily be altered or even inserted inverted as seen on the below covers.

There are many more examples of date error, but mostly of having the wrong date on First Day Covers.

Please feel free to share your examples.