Some people use many Bitcoin wallet specially those people who wants to earn a lot of bitcoin every week for signature campaign plus many accounts here in bitcointalk. As for me i only use 1 Bitcoin wallet , 1 is enough for me to received and send bitcoins.
it is very possible. bitcoin wallet reproduce address can also bring opportunities to earn more money. we are free to use it. it is a choice.
I believe the sole reason why any most people are here is primarily to earn some Bitcoin in which when you do you cant keep in your hand or get into your mail like PAYPAL but into your bank account which in this case your wallet which can be online (mostly popular and very flexible recommended for newbies) or offline used by average and pro-users. This wallet now generates addresses that can be used to receive money for different purposes and also to avoid tracking of your funds...