We analyze the response of two delay-coupled opto-electronic oscillators. Each oscillator operates under its own delayed feedback. We show that the system can display square-wave periodic solutions which can be synchronized in-phase or out-of-phase depending on the ratio between self- and cross- delay times. Furthermore, we show that multiple periodic synchronized solutions can coexist for the same values of the fixed parameters. As a consequence, it is possible to generate square-wave oscillations with different periods by just changing the initial conditions.