RCPs and previous scenarios were created exactly to avoid such duplication, and the inevitable initialisation inconsistencies that would ensue. (skepticalscience.com)
The different runs produce outputs from different initialisations. (skepticalscience.com)
Decadal climate prediction is immature, and uncertainties in future forcings, model responses to forcings, or initialisation shocks could easily cause large errors in forecasts. (fabiusmaximus.com)