EPIPHONE began making the Don Everly SQ-180 (MODEL EAQ1) in the early 1980s. The Epiphone SQ-180 was an authorised version of the 1962 Gibson Everly Brothers flat-top acoustic with its thin J-185 style body, star inlays and double tortoiseshell pickguards. This model was referred to in earlier catalogs as simply the SQ-180 - but when the Neil Diamond SQ-180 was introduced in 1999 they had to start calling this one Don Everly SQ-180 to differentiate it. It finally discontinued in 2006. The peghead shape and logo changed in 1989 and again in 2002 and by 2006 there was a Don Everly signature on the peghead.
Source: Epiphone catalogs 1991 - 2002
Source: Unofficial Epiphone Wiki - SQ-models