That's a very odd hole placement.

'Two holes', drilled and tapped, would suggest they were for a Receiver 'Peep' Sight.

However, as 'mgbill' states, the placement is peculiar and in the middle of the receiver.

Receiver sight holes are usually located behind the serial number.

Weaver scope mounts use four holes and William's scope mounts use three.

(I don't know about Echo mounts and other obscure ones).

FWIW - Here are some sight and mount examples.

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