Hello! I'm looking for yaoi manga with guys fighting over the title of Seme...
Example: Docchi mo Docchi

Hi there!
The only ones that come to mind right now are
the battle of the wolves and puchitto Hajiketa
I would really recommend the second one. It definitely fits the criteria and its also really cute 😀
There is also harenchi no susume which is kind of like that as well

They both want to be the seme in Mousou Elektel

Try this: http://www.mangaupdates.com/series.html?category=Seme+x+Seme

You could try this also: http://www.mangaupdates.com/series.html?category=Seme+Turned+Uke