This is not new. Not many organizations within the BLGO system can say that their concepts are original. Case in point. Consider Alpha Phi Fraternity. No...not Alpha Phi Alpha....Alpha Phi Fraternity. Alpha Phi Fraternity is the first women’s organization to use Greek letters as an emblem. They were founded in 1872. They are not called a sorority because they were founded before the term sorority was used. Their colors are silver and bordeaux but they often use pink and green in their designs. Even their website is designed in pink and green.
You can view it here.
http://www.alphaphi.org/about_us/symbolsofalphaphi.html
Their official symbol is the Ivy Leaf. This may be a coincidence but being that Alpha Phi Alpha was founded an hour away from where Alpha Phi was founded, it is plausible that some symbols may have been borrowed in the founding of Alpha Kappa Alpha. Being that the formation of the first BLGOs was, in itself, an act of defiance to the "all white" fraternities and sororities, it's not unlikely that some the symbols were used to make a political statement. This is just my conclusion though. There is nothing to support that this why some symbols are similar.
Please, members of AKA and Alpha, DO NOT get upset with me about posting this information. You may have already known this though, I am not familiar with what your organization teaches you about your founding and the origin of your symbols. I just wanted to point out to those who don't know much about fraternity and sorority history that nothing is new under the sun when it comes to some of the symbolism used in BLGOs.