Neither the “Doppelrune” (Doublerune) nor the “Siegrune/Sig-Rune” (Victory rune) are historic runes and were created 1929 by Walther Heck. The “Siegrune” itself wasn’t even inspired by the germanic “sowilo” rune (ᛋ), Walther Heck himself stated, that he created it, as he disliked the soft form of the “S” in the latin alphabet and wanted to provide an alternative to the “Fraktur” style that was commonly used in germany at that time.

This ᛋ is “sowilo/sigel/sol”, the germanic rune for sun

This ϟ is the “Siegrune”, created 1929 by Walther Heck as an alternative to the letter “S” and was used by the Nazis

This ϟϟ is the “Doppelrune”, also a creation by Walther Heck and used as a symbol for the SS