The phrase "did duty as" essentially means serving a purpose or fulfilling a role or responsibility in a temporary or substitute manner. It is a colloquial expression primarily used to describe someone or something that is functioning as a replacement or stand-in for another individual or object.
When someone "did duty as" something or someone, it implies that they assumed the duties, obligations, or functions typically associated with the role or position under consideration. This phrase suggests that the individual in focus was not the original or permanent choice for the task at hand, but rather filled in temporarily due to exigencies, unavailability, or other circumstantial reasons.
For example, in the context of a play, if an actor were unable to perform due to illness or unforeseen circumstances, another actor might "do duty as" a replacement, stepping in to assume and perform the role. Similarly, in a team sport, if a regular player is injured, a substitute or reserve player may be called upon to "do duty as" a substitute, taking over their responsibilities on the field or court.
In summary, "did duty as" signifies an interim or substitute performance of a role, emphasizing that the individual or object is functioning in a capacity that is not their primary or original purpose, but rather only temporarily filling the position for a specific period or situation.
