What is the source for those symbols? Do we know that the first one is anything more than a creation of the Hasbro Marketing Department?
It would make sense that the original Sith Empire would have iconography. They had a huge, powerful empire and no adversaries (save each other). Emblems of that power would be emblazed across the entire empire to make sure that those subjugated would never forget that the Dark Lord of the Sith was there ever-watchful master. However, once the Sith went to the "Rule of Two" and stealth, secrecy, and deception became the ways of the order... it just doesn't make sense to use symboles and iconography. That's just evidence for enemies to find and identify you with. There are only two Dark Lords of the Sith at any given time, so why would they need iconography? Why would they risk a means by which to be identified?
I can imagine that once Sidious and Vader have killed what they believe to be the last of the Jedi, then there would be no need to avoid symbols and emblems any longer... but you still have the Rule of Two and no need for special iconography. It's superfluous.
i'm pretty certain that there was never any official sith insignia, and i think all those ones on the packaging are just made up by hasbro.
however, if you look through the various dark horse knights of the old republic and sith lords comic series, there are a bunch of runes and symbols shown in there. some of the sith have them painted onto the sides of their ships, and ulic qel droma and exar kun had them tattooed on their foreheads.