LM27761: Can combine 2 of the LM27761 Outputs in parallel to get 500mA Output current capability?

Are you powering an RF data converter? This TIDA can likely also be used: www.ti.com/.../tida-01405

I don't think paralleling these ICs makes too much sense, as they contain both a charge pump and LDO. If you need to use an LDO, use a bigger inverting converter (like the above TIDA) and then use a discrete LDO to go further down in voltage.