Moreover, if there are two bimetallics, it'll often be the case that the outer-inner ring will be Silver-gold colour combo for the higher value and Gold-silver for that of the lower denomination (à la 2€ & 1€ and 5zl & 2zl). However, if there is just one bimetallic, it used to be Silver-gold (eg 500lire, 10Bhat etc)...though now it tends to be Gold-silver (eg Indian Rs10, Brazil R1)
More than one bimetallic but same color combination retained is Mexico.
In case of India, Prof A K Sinha, who designed the first bimetallic, had recomended Rupees 5 to be bimetallic too. That somehow was not accepted and steel 5 Rupees was issued. Had that been issued, it would have been Silver-gold.
Also, not all bimetallics have to be two toned. See Algeria 10 Dinar, Cupro Nickel outer ring and Aluminum Inner portion.