The thought is the "Dos Ciervos" dates to when Imperial Cutlery of RI had a Mexican arm of the business with help from Foster Grant (the sunglass people). In the mid 60's, Imperial sold the Mexican operation to Associated Spring of Conn, who kept it running till the 80's when it was sold again. The "Dos Ciervos" stamp is from that 60's - early 80's period. For more of the whole story, here's a big article on Imperial Mexico -
Edit - the article doesn't link well -
https://www.google.com/search?q=Pottery+and+Royal+Poincianas+imperial+knives , it should be the first link in that google search.
It's a rare stamp, but really only of interest to hardcore Imperial collectors.
Edit #2, working link -
http://www.collectors-of-schrades-r.us/articles/Pottery and Royal Poincianas.pdf .