http://www.mangago.zone/read-manga/twins_labyrinth/
this one maybe but the relationship isn't between the twin brothers
Yaoi with twins:
http://www.mangago.zone/read-manga/1_5_darling/
http://www.mangago.zone/read-manga/sora_o_daite_oyasumi/
http://www.mangago.zone/read-manga/koisuru_omocha/ (ch.5)
http://www.mangago.zone/read-manga/yuukyuu_no_kanata/
http://www.mangago.zone/read-manga/trouble_love_attack/
http://www.mangago.zone/read-manga/nureru_karada_yamakami_riyu/
http://www.mangago.zone/read-manga/kimochi_no_yukue_meiji_kanako/
http://www.mangago.zone/read-manga/alluring_sentiment/ (ch.1-2.)
http://www.mangago.zone/read-manga/tsuki_no_ookamiotoko/
http://www.mangago.zone/read-manga/kouya_no_seifukuou/ (ch.3)
http://www.mangago.zone/read-manga/katayoku_no_sokubaku/
http://www.mangago.zone/read-manga/yononaka_wa_bokura_ni_amai/
http://www.mangago.zone/read-manga/okubyou_na_junjou/
http://www.mangago.zone/read-manga/blt_burning_love_twin/
Any yaoi with twins in it?