I recently purchased a small bulk lot of common U.S. revenue stamps on
ebay, and in it there were about 1000 Scott # R152a and R152b (no R152c sadly), and decided to use it as an opportunity to do some flyspecking.
I've not seen any definitive references to plate varieties on R152; it wasn't included in the Shift Hunter Letters. There have been a couple of brief articles in The American Revenuer, showcased below.
For each stamp I show an image, a second copy of the same image but with arrows showing the diagnostic points, high-res cutouts, and then a link to a 3200dpi high-resolution image of the full stamp.
If anyone has other types of R152 varieties or any platings/references, please post them. Thanks.
You may need to click on images to view them at full size.
Doubled framelines. Mentioned in this 1966 TAR article.

1. Doubled frameline at upper right; twisted transfer or a recutting?



High-res image:
https://revenue-collector.com/zoomify/5401.jpg2. Doubled frameline at upper left.



High-res image:
https://revenue-collector.com/zoomify/5402.jpg3. Another doubled frameline at upper left.



High-res image:
https://revenue-collector.com/zoomify/5403.jpg4. A doubled frameline at bottom.



High-res image:
https://revenue-collector.com/zoomify/5404.jpg5. This one is likely a printing anomaly rather than a plate variety. Many of the details along the left side are mushy, possibly the result of the paper bouncing against the plate? Also some muddiness in the portrait.


High-res image:
https://revenue-collector.com/zoomify/5405.jpg6. A tool gouge or plate crack in the numeral 2 at bottom, but also some anomalies in the NTS of CENTS.



High-res image:
https://revenue-collector.com/zoomify/5406.jpg7. Extra frame/guide line at upper right.



High-res image:
https://revenue-collector.com/zoomify/5407.jpg8. Presumably the Scott-listed double transfer.
From the July 1985 issue of The American Revenuer:




High-res image:
https://revenue-collector.com/zoomify/5408.jpg9. And a more bold example.



High-res image:
https://revenue-collector.com/zoomify/5409.jpg