can there be more than one tranformer in a circuit?

Question

if so how are they kept from interfering with each other

Answer 1

Yes. ~
They can work in tandem or in parallel. Also, 1 may inject power and a few others may extract it.
The whole electric power grid is a perfect example of that.

Answer 2

There can be many transformers in a circuit. One form of coupling amplification stages together is "transformer coupling"; the transformer, passes only the AC component of the signal and not the DC, therefore not interfering with the bias voltages. Most often, transformer coupling is used for impedance matching where power transfer (as opposed to voltage transer) is important and for tuned circuits, where the transformer windings act as part of a resonant circuit.

If transformers are well-made, the magnetic fields are well-confined to within the core. In addition, transformers are shielded. In laying out a circuit, two methods are used to minimize interference: keep the transformers far apart, and orient them at right angles to each other.

Answer 3

There can be as many transformers in a circuitas you need. If they're well designed and built, the leakage flux is very small and they're not terribly susceptible to being driven by external fields.
You can also minimize cross-coupling with careful physical layout, shielding, etc.

Doug