About cascode tuned circuits
At resonance, a parallel tuned LC produces zero phase shift hence, with two parallel tuned circuits separated by a buffer, the effect is the same i.e. zero phase shift apart from the inversion due to the buffer being an inverter.

Parallel LC filter on-line calculator: -



If the LC were a low-pass resonant circuit then there would be two lots of 90 degrees phase shift for the whole circuit and a further 180 degrees due to the inversion. Same for a high-pass LC circuit.