Can PRACH (either type 1 or 2) and PUSCH share time resources (e.g. slot and symbol) if they differ in frequency resources? I read that PRACH for a single UE must be ahead by at least 2 symbols from the corresponding PUSCH. 

What happens when PRACH from one UE coincides with PUSCH from another UE? Would that ever occur in reality?

Thanks,

Prach & Pusch each has own separate time domain and frequency domain. The NR must extract prach preamble from its time domain resources(1 subframe or so) and its frequency centre. Prach is sent by any UE anytime asking to attach and it is independent of pusch.

Think of LTE or NR ofdm signal as a basket of many signals...