This is a question about about a situation that will only happen once (at the most)... but I was just curious about it.

Scenario: I see something I want to bid on and place a bid manually. I then start thinking "I really don't want to lose this" so I hunt around for some suitable snipe software and decide Myibay is the one I want. So I install it - and add my max bid on the auction in question - but the current highest bid is mine.

Will the software know it's mine - or will it jump in with 5 seconds to go and overbid my own bid?

As I said, it's not big deal - but just curious what would happen.

You can not outbid yourself, so it's safe to bid manually and then set a higher bid in the sniper.
If nobody else bid, you will not increase your price by sniping.