In recent years, there is growing evidence that the combination of metabolic- and receptor-targeted positron emission tomography (PET) imaging can optimize treatment planning for metastatic cancer patients. However, the corresponding diagnostics, performing multiple PET/CT scans, are currently not common clinical practice because of costs and availabilities issues of the infrastructure. The DUPLET project aims to leverage particle physics technology combined with state-of-the-art clinical expertise and newest radiopharmaceutical developments to combine multiple diagnostic procedures into one single scan to make optimal treatment selection viable for daily clinical practice.