The "220" bezel ... such a cool oddity in the Speedmaster history!
Omega introduced in 1970 a new bezel version (e.g. no "accent" on the "Tachmetre"). BUT: somehow quality control missed the obvious printing mistake (220 instead of 200) and a small batch of watches hit the market.
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I believe they're all straight writings, too . . .
. . . so there's a backdoor confirmation of originality. If memory serves correct, there's a defined range of movement numbers for these, so in effect a 220 is more likely to be confirmed as wholly original than other references without having to ask for ...
Found this pic . . .
. . . in my files, S. Taken exactly five years ago at a road show for a Speedmaster auction; note the double-signed dial. Art ...