I would rule it a call, as it doesn't meet the criteria of a raise under rule 31 and does not require clarification by rule 33. Rule 33 is better described by, for example a player betting 1,200 and a player immediately throwing two 1,000 chips unannounced into the pot, in that circumstance it would clearly be a call as it does not meet the criteria of rule 33.
Regards
Stuart