Oqpsk input to output mapping

I have used OQPSK block with samples per symbol as 2, phase offset as zero, input type- bit, symbol mapping- binary, output type -double, pulse shape- half sine and rate option as enforce single rate processing. Unlike QPSK which gives 2 waveforms(real and imaginary), Oqpsk output is 4 waveforms(2 real and 2 imaginary).

I would like to know the reason for getting 2 complex signal instead of 1 at the output of OQPSK block.

I am attaching the block diagram for OQPSK