re: "hiring multiple freelancers to ensure deadline is met. I'm new at hiring freelancers for projects, so this advice confuses me. How does one go about hiring more than one on a limited budget?"
When it comes to hiring multiple freelancers:
One purpose for hiring multiple freelancers is to save money overall on a project.
Another purpose for hiring multiple freelancers is to hedge one's bets when there is an important deadline.
These are separate purposes, and entail different strategies when hiring multiple freelancers.
The more important a DEADLINE is, the more it make sense to spend MORE money in order to hedge one's bets.
If a client really wants to guarantee that they'll get the work done they need on time before an important deadline, than the client may be willing to spend more money than if the client has no particular deadline. Such a client may be willing to hire three or four redundant freelancers and pay them all. Cost is not the critical factor.
If a budget is limited, then the client can be very transparent with the freelancers she hires. Tell them that there is a certain amount of work that needs to be done, and she is hiring a team of freelancers, and when the work is done, the project is over. Hire using ONLY hourly contracts. When you have obtained the work you need, then close all the contracts.
If the client really wants to avoid paying for redundant work, the client can even put all the freelancers in communication with each other so that they don't do redundant work.
For example: If the task is to do background removal for 50 product photos, different freelancers could work on different images until all the work is done. It isn't necessary to assign the same photos to more than one freelancer.
* * *
Hiring using multiple freelancers in order to save money overall - and not because there is an important deadline - involves different strategies:
If you have a limited budget, you are even more likely to benefit from hiring multiple freelancers.
Client needs to have a business website created.
Client hires one freelancer.
Client spends $5000.
That's fine. Because that client had an unlimited budget.
But ANOTHER client has a limited budget.
So client hires 6 freelancers.
Client finds that two never log time and deliver zero work.
Client finds that two do terrible work.
Client finds that 1 does great work, but charges a lot.
Client finds that 1 does great work, and charges much less.
Client stops working with 5 freelancers after only paying for two or three hours of work. (Client doesn't pay the first two anything, because they did no work).
Client continues working only with 1 freelancer - the one who provides the best value.
Client spends $2500 for the same website.
Hire multiple freelancers for a limited time or limited tasks. Continue working only with those who provide you the best value - work that has the quality you seek, for the best price.
That might mean paying a freelancer $10.00/hour. That might mean paying a freelancer $90/hour.
If freelancer "A" can finish Task X in 10 hours, charging $10.00/hour, but freelancer "B" can finish Task X in 1 hour, charging $90/hour...
...and if the quailty is the same...
...then that means that freelancer "B" (whose hourly rate is more expensive) is the better value.
Keep in mind there is no way to know for certain how a freelancer will work out unless you hire them.