I have asked about these Gold coins in my Yahoo-groups. Jan Lingen, O.N.S., from Holland gave me this answer;

These are gold Fanams from Orissa region. They have been attributed to thee Imperial Ganga family of Orissa. The couchant bull on the obverse is the dynastic emblem of the Eastern Gangas and hence the attribution.The history of this dynasty starts with Vajrahasta Anantavarman, the father of Rajaraja and grandfather of Anantavarman Chodaganga. The eastern Gangas originated from South India from a place called  Kolahalapura as in the inscriptions, now identified as Kolar in Karnataka. The dynasty ruled from 11 th.-15 th. century.

The dates on the reverse denotes  regnal years of the ruling kings, which so fare hasn't been attibuted to particular rulers of the dynasty. A detailed discussion can be found in; Early and Mediaeval coins and currency systems of Orissa, c. 300 BC-1568 AD, by Snigdha Tripathy ( Calcutta. 1986 ).

		Fanam, Au			Fanam, Au			Fanam, Au
ø 10.5 mm	0.44 gram		ø 11.5 mm	0.45 gram		ø 10.5 mm	0.49 gram
		Orissa,Fanam.01			Orissa, Fanam.02			Orissa, Fanam.03

		Fanam, Au			Fanam, Au			Fanam, Au
ø 11.0 mm	0.53 gram		ø 10.0  mm	0.45 gram		ø 10.5 mm	0.46 gram
		Orissa, Fanam.04			Orissa, Fanam.05			Orissa, Fanam.06

		Fanam, Au			Fanam, Au			Fanam, Au
ø 10.0 mm	0.46 gram		ø 10.5 mm	0.46 gram		ø 10.5 mm	0.46 gram
		Orissa, Fanam.07			Orissa, Fanam.08			Orissa, Fanam.09

		Fanam, Au			Fanam, Au			Fanam, Au
		cm.			cm.			cm.
ø 10.5 mm	0.46 gram		ø 11.0 mm	0.46 gram		ø 11.5 mm	0.46 gram
		Orissa, Fanam.10			Orissa, Fanam.11			Orissa, Fanam.12

		Fanam, Au			Fanam, Au			Fanam, Au
		cm.
ø 11.5 mm	0.47 gram		ø 11.0 mm	0.48 gram		ø 10.5 mm	0.42 gram
		Orissa, Fanam.13			Orissa, Fanam.14			Orissa,Fanam.15

		Fanam, Au			Fanam, Au			Fanam, Au
ø 10.0 mm	0.44 gram		ø 10.5  mm	048 gram		ø 10.5  mm	0.49 gram
		Orissa, Fanam.16			Orissa, Fanam.17			Orissa, Fanam.18