Up until 1974 I was an out and out United fan. It was only when United had hooliganism problems in the early 70's that I switched to non league and Altrincham. That said I support both Altrincham and United, but Alty are my first love and I would never go to United if Alty are playing at home, as I cannot get to many away games due to my family commitments. I get to around 10 United matches a season on average, but all of Alty's home games.
I follow both clubs and always watch United on TV. I used to work away from home a lot during the early 80s's and if there was a match on I would go to it. I did not support the club but I went. It was not loyalties but a deep love of the game of football. I am hopeless at playing it, but have always enjoyed watching any game, not matter who is playing.
So no, there is no harm in supporting more than one team, I follow Altrincham, Man U and England; and have mostly enjoyed watching all of them over the years and have many happy memories. I started by watching the United teams of the 60's stood on a 3-legged stool at the back of the Stretford End paddock with my dad and brother. I can still hear 'I don't want our loving to die' playing by The Herd over the tannoy while waiting for Best Law and Charlton et al to appear on the pitch. I would loved to have watched the Busby Babes of the late 50's, but I was only 5 months old when they had their tragic plane crash.
I also have even more memories of Alty, starting with the John Hughes/Gerry Casey years up until the present day. Yes, it would be true to say over the years football has been a major part of my life, and these memories I will take to my grave with me. They are a part of us all, both in the past and the future, and we all hold our own dear memories. So, AltyAzz, you are no different from me, you just enjoy the game and reap the benefits of following two teams, which means even more football!!