Three professors have promised to write me recommendation letters for PhD program applications. I want to apply to the program where one of them (Prof.A) is a professor. I was in his summer research program and I'm still a member of his group. He knows me pretty well and speaks highly of me. I talked to him about the application and he told me I could apply directly.
Do I need to find another professor to write me a recommendation letter for Prof.A's program? It seems weird to use his recommendation letter to apply for his program. But he knows me quite well and I don't think the SOP or recommendation will give him any surprise information about me. The three professors are very familiar with me and I don't think other professors can write letters stronger than them.