I am running several campaigns with similar targetting on POF. (small budget like $10 per day for each campaign and distribute ASAP)
Is that possible I am bidding against myself and how to avoid it?
To be honest, that's the wrong mindset. Biding against yourself is fine, on POF your always going to have to bid against someone, why not it be yourself? POF has limited high quality traffic, why not want more for your self? (this is assuming they are different angles)
Bidding against yourself serves 2 purposes:
1. it makes it harder for other people to enter that targeting on a lower bid.
2. it gets you more profitable traffic. (2 campaigns at a 30% ROI is better than 1 at 50%)
Also on the 110x80 placements, unless your running tons of campaigns, its pretty irrelevant:
3 campaigns at a max session depth of 25 and frequency cap of 3, can take up 9/75 of the space 12% ... Increase to 4 campaigns and you would be bidding against 12% yourself and 88% everyone else.