base.py: handle any duplicated indices when creating dataframe
Created by: qais-yousef
When running Lisa tests on fastmodels duplicated timestamps happen frequently and cause some failures down the line.
The duplicated timestamps are not bad themselves and a side effect of simulated time not having good enough resolution.
Handling this duplication at the dataframe creation seems to be the most generic and future proof solution.
Signed-off-by: Qais Yousef qais.yousef@arm.com