How to properly mark a linocut prints series
As far as I'm aware (I'm not a professional artist) the artist should strive to make each print of a series as equal to all other prints as possible. However, if the artist intentionally introduces non-reproduceable variations in how the paper is printed or alters the print by hand, it can be considered a &quot;Varied Edition&quot;, &quot;Variable Edition&quot; or &quot;Edition Variable&quot;.
You as the artist decide which prints meet your own quality standards. If you want to eliminate as much variation between prints as possible, destroy the prints with too much variation. If you apply several colors at the same time and random color variations (due to leftover color from the previous print) are part of your artwork and you like the way they came out, keep the print and sign it. You could also decide to print an entire series with a different paper or different colors for each print. It's your freedom as artist do decide how you define a series.
Artists who decide to categorize their series as a Variable Edition usually label prints with something like &quot;VE 1/10&quot; or &quot;1/10 VE&quot;. That doesn't mean that prints without that addition cannot be varied, it just means that the artist consciously labeled the series as variable. As always, there are no hard rules.
Some short and informative sources are:

What is a Variable Edition Print?
Variable Editions