It is not possible to directly change an alarm text because the ‘label’ and ‘comment’ attributes do not support expressions. However you can filter the appearance of one or the other alarm by incorporating an additional condition in the ‘value’ attribute of each of them so they only activate when they should. For example if a variable determining a device is ‘emabledDevice’ then you can have:
value = enabledDevice==1 && PLC_ai16_alarmas_0_1999;
In such case the alarm will only be activated when enabledDevice is 1, you get the idea.