I hope they are 6.2W rather than 6.2 V, as the latter would not work well on mains voltages...
As said, these things draw very little current, so older dimmers (and wiring) sometimes need updating before they work properly with the low-current systems.
I replaced some dimmable 300W halogen bulbs with 19W (dimmable) LEDs, and wnen on full power it's fine, but as soon as we try to reduce the power, the bulbs flash in an unacceptable way.
If you want all three bulbs to be LEDs, then you will probably need to either replace the dimmer switch, or add some ballast (more resistance) to the circuit.
Alternatively, things will probably be OK if you have 2 LEDs and one incandescent bulb in the fitting. It will save energy, but may look a little weird..
Incidentally, dimmers tend not to be rheostats (pure resistance) that reduce the level of the power, but electronic devices that chop up the current into a series of pulses.
I replaced all bulbs on our house with LEDs a couple of years ago and it is a big saving, but there are a few small compromises to be made.