My IMEI Turns To 00000000000000

Does a dual sim android phone always return same IMEI when imei slot meaning this means that 3G4G tablets, laptops with PCMCIA wireless internet If you have a dual-SIM phone, you'll see two IMEI numbers, one for each SIM slot imei slot 1 IMEI 1 and IMEI 2 are the International Mobile Equipment Identity numbers of a dual-SIM phone Each SIM slot has its own unique IMEI number

imei slot meaning my phone has two IMEI numbers, when transferring numbers does public mobile need the IMEI of my used SIM slot or the avaliable SIM slot?