1. Apparatus for processing data comprising: queue storage to store a queue of event entries corresponding to notifications of events from a source to a destination; a comparator to compare a received event entry with at least one previously received event entry to detect a match; and event entry merging circuitry to merge said received event entry with said at least one previously received event entry in response to said comparator detecting said match; and wherein: said event entries include a translation error event entry indicating occurrence of an address translation error; said address translation error corresponds to a translation table data miss and said translation error event entry triggers said destination to perform a page table data walk to a page of translation data within page table data corresponding to said translation table data miss; said translation error event entry includes error address data indicative of an address of an attempted access corresponding to said address translation error; said comparator is configured to compare error address data of received translation error event entries to detect said received translation error event entries corresponding to a same page of translation data within said page table data; and said event entry merging circuitry is configured to merge received translation error event entries having matching error address data.