And there shall be eight frames refers to the six regular frames in verse 22 plus the two corner frames in verse 23. With their bases of silver is literally “and their bases of silver.” These bases are like those mentioned in verse 19. Sixteen bases is the number needed for eight frames, with two bases per frame. Two bases under one frame … under another frame simply means, as Good News Translation puts it, “two under each frame.” Contemporary English Version has a good model: “Altogether, this back wall will have eight frames with two silver stands under each one.”

Quoted with permission from Osborn, Noel D. and Hatton, Howard A. A Handbook on Exodus. (UBS Helps for Translators). New York: UBS, 1999. For this and other handbooks for translators see here .