There are many same Drivers' name but different version number. Which shoule be kept,or I need to keep them all.How does MDT work when it comes to the step of selecting drivers.

If you use the "Install all drivers from the selection profile" option then every single driver will be placed on the machine and made available to Windows. This includes multiple versions of the same driver. Then when Windows decides that it needs a driver for a particular device it will interrogate it driver store and pick the best driver for a particular hardware ID.

If using "Install only matching drivers from the selection profile" then when running the Inject Drivers action, MDT will scan the system for all PNP device IDs and then pick the best driver per device and only copy that to the C: drive. "best" being the latest driver version for a device ID.

I prefer the "Install all drivers from the selection profile" and being very careful about what drivers are included in that profile.