George Jones & Tammy Wynette - The Classic Christmas Album (2013)

This is a "parallel anthology" rather than an album of duets: Jones and Wynette sing together on the first and last tracks (the two sides of a 1973 single), but the other selections are solo recordings. All of the Wynette selections are drawn from her 1970 LP Christmas With Tammy. Jones never cut a Christmas album, so his tracks are culled from singles and multi-artist holiday compilations released between 1957 and 1986. This is not quite a "complete" George Jones Christmas compilation, but it's close: the only tracks missing are "My Mom And Santa Claus" (1962, 1968), "O Come, All Ye Faithful"(1980), and the 1968 re-recording of "Lonely Christmas Call."
This compilation came in at #7 on Rolling Stone's 2013 list of "40 Essential Christmas Albums." Apart from the understandable but mistaken assumption that Jones recorded his own Christmas album, the review is right on the money:
"The title is a misnomer: this 2013 collection is cobbled together from a Jones Christmas album, a Wynette Christmas album, and some holiday duets they recorded while married in the early '70s. But the songs belong together, even if the singers didn't: two of country music's most beautiful voices taking turns singing lonely Christmas laments. Wynette's performance of "White Christmas" is just as melancholy as Jones's "Lonely Christmas Call," making this the perfect album for nursing a holiday heartbreak."