In the area of database/computer security the problem of polyinstantiation is widely recognized. The research on polyinstantiation can be considered morally questionable, since it involves lying. This paper analyses whether the research and practice on the problem of polyinstantiation is morally blameworthy or praiseworthy in a general sense. The morality of polyinstantiation shall be critically analysed from the viewpoint of a moral philosophical framework. The moral philosophical framework used includes 1) Kantian ethics, 2) the "impartial" universality thesis advocated by Hare, Rawls, Gewirth, Jewish- Christian ethics, and Confucian ethics, 3) utilitarianism, and 4) Theory of Information Ethics (IE) by Floridi. The result of this analysis suggests that polyinstantiation is morally questionable, at least in the light of the chosen moral philosophical theories. The aim of the paper is not, however, to deem polyinstantiation as morally wrong altogether, but to provide researchers and practitioners with tools and insights for analysing the morality of polyinstantiation in different cases. Moreover, this paper sheds new light on the relevance of IE. The results suggest that, as far as polyinstantiation is concerned, traditional theories seem to be at least as adequate as IE.