This paper tests if Second Price Vickrey Auction (SPVA) and Discrete Choice Experiment (DCE) are isomorphic and whether lack of isomorphism is due to value-elicitation, value-formation or both. We conduct an artefactual field experiment that combines induced-value (IV) and home-grown (HG) procedures using SPVA and DCE. IV preferences are elicited for tokens and HG preferences for multi-attribute lasagnes. Attributes are healthiness and environmental sustainability. Our results suggest that HG preferences differ across elicitation methods. This discrepancy is due to value-elicitation and value-formation. DCE is the most demand-revealing approach and provides the highest premiums for healthy and environmentally sustainable lasagnes. Acknowledgement :