One name is as good as another. Not wise to use your own name.
6 seconds sound clip from the The Good, the Bad and the Ugly (1966) movie soundboard.
You can hear this line at 01:40:54 in the Blu-ray version of the movie.
Quote context
[...]
- You were captured near Fort Craig.
- Well, if you were with Sibley, that means then that you were coming from Santa Fe.
- Was it hard crossing the desert?
- Mmm-Hmm. Very hard. Especially if you don't have anything to drink.
- Why are you going under the name of Bill Carson now?
- One name is as good as another. Not wise to use your own name.
- Like you. I'll bet they don't call you Angel Eyes. Sergeant Angel Eyes.
- Like a little music with your meal, Tuco?
- Music? Yes, it's very good, very good for the digestion.
- So... Bill Carson's a fake name, huh?
[...]