Ban Liang Ancient China Double-Charactered [opgelost]

Two separate coins, both similarly marked.
The one on the left is 3.7g, on the right 4.5g.
Both are 23mm.
I believe these are from the Western Han dynasty.
Every Ban Liang ancient Chinese coin that I have seen only has one set of the Chinese characters 半兩, but both of these coins, taken from the same lot, have two sets of these characters.
Any ideas as to what would be a more proper identification?
Thank you.

George A. Fisher Jr.
Fisher’s Ding (Ding Fubao’s catalog selectively translated), 1990.

As you indicated, these are Ban Liang coins. Your exact coin is listed on page 49 as Fisher #420. The other coins with two characters were valued at $20; the four character coin was valued at $80. Western Han Dynasty, not dateable.

I also checked
Davis Jen: Chinese Cash (not listed),
Fredrik Schjöth: Chinese Currency (not listed),
James H. Stewart Lockhart: The Lockhart Collection of Chinese Copper Coins (not listed),
Arthur Braddan Coole: Encyclopedia of Chinese Coins, Earliest Round Coins of China, v7 p62 #9144.

Thank you very much for the information, very helpful!