I'd be interested to know if anyone has ideas about such counting.

Whilst I know next to nothing about this particular aspect of Bing's popularity, I'd think that Decca were counting the two "main" recordings of White Christmas as one. After all, to a great extent they preserved the fiction that the '47 re-recording was the original, showing the incorrect earlier date on all LP and CD issues despite usage of the '47 version into the 1990s.

In addition there was no need for them to keep different counts for any rights purposes.
As to the other titles  - -   ?

Where is the Bing Crosby world? I will not give up. Record sales .long ago are important-always noting times of release. .I would like to note Bing's ORIGINAL 1931 :"Where The Blue OF THE NIGHT ,recorded in 1931.Despite Jack Kapp's (later) re-recordings on Decca, as well as disregarding them ,is it fair to assume that THIS recording ,INCLUDING DECCA's REISSUE of THIS ORIGINAL, in the 1940s & 1950s,on 78 & 45 ,as well as on (US) BRUNSWICK (silver) REISSUE up to 1939,as well as counting sales outside of the US got to over a million copies sold ?

Malcolm/ As a record collector of many, including Bing, a fan is always 'however much we would like them'. Perhaps 'taste' of a review of a recording is another matter, as I have noted in my own book "Just Remember This'. Yet THESE CROSBY SALES DID EXIST,& more so should be found .Perhaps in writer royalties credit, of payments to someone? Or annual record sales credit to Bing. Maybe Gary Giddins ,who seems to have gotten a lot of i(old) info, may find some? MORE recent claims (AMERICAN MASTERS) in 2014 as BING BY THE NUMBERS finds Bing 'close to one billion records ,tapes, compact disc & digital downloads'. As also noted (here) , Bing as just scored (2020) some very good  US (Billboard) charted success, in fact in the last few years, since Billboard CHANGED BACK it's policy for HOLIDAY songs, which stupidly omitted a lot of Christmas songs ( 5 decades) for a lot of other artists, but ESPECIALLY for Bing-on it's main Hot 100 pop chart. .So ,in light of all this,& these more recent sales claims, we should find out which claims & statements are valid .I think that we may just like them.

Australians who wish to learn the sales of records when we bought those 78 rpm shellac discs are fortunate. For most of the 1930s and 1940s EMI affiliates dominated the record industry with production by The Columbia Graphophone Company in Sydney. Each month the sales were recorded on small cards. When EMI decided that it no longer wanted to keep those cards they were sent to The National Film and Sound Archive in Canberra. David Kent of Sydney was able to make copies of the cards and kindly allowed me to record the sales of most of Bing's Aussie-made discs.