Scenario: I recently signed a full-time contract with an ICT multi-national company 'A' with one of its offices based in Perth CBD in Western Australia to work as an engineer Mondays to Fridays 08:30am to 05:30pm AWST working hours. Now, simultaneously, I am offered another opportunity (to work from home as an independent contractor offering software testing service for a consultancy firm 'B' based in Brazil that will pay me in US dollars from overseas, and the PDF document contract mentions terms and conditions subjected to Brazilian Civil Code. Note, I have not signed this other contract yet.
Question: Is it possible to negotiate a deal such that I can offer service to this overseas Brazilian 'B' company during Saturdays and Sundays and Australian public holidays and times whenever they will be off from the working hours of Australian company 'A'? Or eventually, will there be any conflict of interest I will need to be aware of and thus avoid this in case if both timeframes of working for these companies clash/overlap? Please help.