Hello again Paul,
A check on the Edinburgh Assay Office website
http://incorporationofgoldsmiths.co.uk" onclick="window.open(this.href);return false; shows no mention of a Matthew Caw but does refer to a Matthew Craw active from 1781-1816. Whether we are looking at one person or two seems lost to history. Unfortunately the website doesn't reproduce an image of any maker's marks to compare with the two you are interested in.
Normal use over a long working life would have worn out more than one maker's punch and replacements would have had to be cut. Replacements often had subtle (and sometimes not so subtle) differences from the original registered at the AO and often the new punch wasn't re-registered.
For what it's worth I suspect there was only one person (Caw or Craw) and the difference in the marks is due to replacement.
Regards,
Mike
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