VLAN in Ethernet switch

Simply, NO. You have to have an unique location and association of your computer (or whatever) on that port to a superior device. Duplication of MAC or IP adresses within any LANs which ultimately can see each others is not permissible. But, if the MAC or IP does not leave you local circuits you can make any mess you like. Why would you even want to do it, I cannot fathom. It is like letting the same phone number appear on two different phone network at the same time. What for?? Incoming calls / packets get totally confused, if the routers do not shut you down first.

Actually, you CAN do it. There are even instances where it might be useful. On the computer side you have to use multi-homing and you would also have to configure your switch properly.