"If you do not tell Caminalda that you are a merchant, she will not initiate an attack on you on the road the next day. You can simply attack her to start the fight; the only lasting effect is an incremental increase in your murder stat."
"This bug is fixed in Oblivion Remastered. She will become hostile after confronting you on the road, whether or not you chose to say you're a merchant. Therefore, killing her after won't increase your murder stat."
Should probably work like in the remaster.
https://en.uesp.net/wiki/Oblivion:Anvil_Recommendation