Made Of Honor problems?

Okay so I'm getting married in July and I'm having four bridesmaids, the only problem is that two of my vary close friends both want to be my maid of honor and I don't want to hurt any ones feelings! I have known one of my friends (Ashley) since I was in first grade and growing up we always told each other that we where going to be ech others maid of honor when we get married. I really want her to be my maid of honor but my other friend (Jenn) has her mind set on being my maid of honor, I already asked Ashley and she said yes but how do I tell Jenn that I already have a maid of honor without hurting her feelings?