Hextech Anomaly if I pay a Ready Rune to get an energy, does that mean I get 2 Fleeting Energy, one from Hextech Anomaly and the other for floating a rune?

Yes — one ready rune can give you 2 floating energy, but only if you use its Recycle ability to fuel Hextech Anomaly.

The full sequence: exhaust the ready rune for 1 Energy ([E] → Add [1]), then Recycle that same exhausted rune for 1 Power of its domain, then exhaust Hextech Anomaly, paying that 1 Power to Add 1 Energy (FAQ #164). Net result: 2 Energy floating for the turn, at the cost of the rune (recycled) and Anomaly (exhausted).

The rune itself only ever gives you 1 Energy from its tap — the second Energy comes from Anomaly converting the power you get from recycling that rune. Both float until your pool empties (end of draw phase / end of turn, Rule 167).