Recollective confabulation (RC) is encountered as a conviction that a present moment is a repetition of one experienced previously, combined with the retrieval of confabulated specifics to support that assertion. It is often described as persistent déjà vu by family members and caregivers. On formal testing, patients with RC tend to produce a very high level of false positive errors. In this paper, a new case series of 11 people with dementia or mild cognitive impairment (MCI) and with déjà vu-like experiences is presented. In two experiments the nature of the recognition memory deficit is explored. The results from these two experiments suggest - contrary to our hypothesis in earlier published case reports - that recollection mechanisms are relatively spared in this group, and that patients experience familiarity for non-presented items. The RC patients tended to be overconfident in their assessment of recognition memory, and produce inaccurate assessments of their performance. These findings are discussed with reference to delusions more generally, and point to a combined memory and metacognitive deficit, possibly arising from damage to temporal and right frontal regions. It is proposed that RC arises from a metacognitive error; an attempt to justify inappropriate feelings of familiarity which leads to false recognition.