It used to be that in the Android app, if you wanted to create two datapoints with the same value you just needed to hit submit twice. Though now the button is disabled while the first datapoint is being submitted, I’d hope to be able to just tap the submit button as soon as it becomes reenabled. But no, the value field gets automatically cleared, so that I have to reenter the value. (This is true even if I enter via a widget with an auto-filled value, so that I have to enter the value by hand anyway the second time.)
The + and - buttons, however, increment and decrement the value which was previously there, so some record of the previous value is indeed kept.