I cannot judge, as I had other monitors before and now only work in the 1-monitor configuration.

In principle, however, this should be technically possible as far as I know, provided the graphics card supports 2-monitor operation (in addition to the laptop screen).

One thing to consider with such parallel operation, however, is that the previous model may have a different resolution and the colour image/temperatures may be different. Therefore, I would always use 2 identical monitors for dual-monitor operation.