I tried chaining two 12V power sources to achieve 24V at the resistor (1k, 0.25W). I got this:
There are a few issues here:
1) The amperage on the left power source is obviously wrong. There is no way the resistor could draw 1.2A.
2) Applying the scope to the resistor, it shows 12V, 12mA which is half of the expected with both figures. Crumb does not seem to add the voltages of the two power supplies.
3) No warning is given that the resistor exceeds 0.25W (probably a resulting error)
Just to be sure, I checked with LTSpice. I took two 12V inputs, chained them and fed their output to a 1k, 0.25W resistor.
The simulation gave a steady line at 24.0 mA, just as expected: