METRANS Danubia currently operates a second 753.6 series locomotive next to CZ LOKO demonstrator unit 753.604. It concerns 753.603, which is owned by SD-KD. For images, see here and here.
Update: It seems that 753.603 was only temporarily used by METRANS Danubia to evaluate multiple working on container services between Dunajska Streda and Haniska, in particular on the Zvolen - Haniska section.
(MG/JS)