You can use more than one booking platform while testing what works, but you need clear rules. The main risk is double booking: two systems can show the same time slot as available unless one calendar is treated as the source of truth.
If you test multiple platforms, keep service names, prices, durations, cancellation rules, and availability consistent. Check calendars daily and decide which platform owns final availability. Add all bookings into that system immediately.
This approach can be useful when a newer platform has a free plan or when you are comparing marketplace discovery against direct booking. After sixty to ninety days, keep the channels that send real clients and let the others coast or close.
Read marketplace vs direct booking for salons before testing multiple channels.