And two more (although these are not weird):
This site says the Tango cover was commissioned by the Mac (but no other info):
http://www.superiorgalleries.com/com...ess_012704.asp
And here's an auction where you can buy a print of the painting used for the Tango cover, signed by the painter. If you click on the link, you'll notice that the image was reversed for use on the album cover:
http://www.leski.com.au/catalogues/a197/TPAI.htm