It was highlighted by one of the collectors . The 3rd Series of RM10 has a shadow printed on Yang Di-Pertuan Agong's portrait. Interestingly, I check across all other denomination notes within the same series, none of them has this "obvious" shadow as printed in RM10 note (take a piece of RM10 note and have a closer look). Could it be the over-printed color that unintentionally spilled over during the printing process? Or could it be a feature that created purposely? Nevertheless, this is not an error note and many of us even not aware of this over-printed color issue.
An over-printed color or shadow on RM10 note