If you have a project, it might be important not to outsource the work to more than one vendor. It might be tempting to use more than one vendor. Especially if the vendor doesnt have sufficient human resources to deliver your project within the expected time frame.
But dont go there. With multiple vendors, there is no single point of responsibility. And when there is a delay, who is to blame? If the code is messy, who is responsible?
And there could be a blame game between vendor-1 and vendor-2, which is unproductive.
So if you only have one project, it is imperative to use only one vendor to be held accountable for everything going on with the project. It’s a different case if you have multiple projects, where then it might be a good idea to diversify your vendors. This is so that you dont get too dependent on one vendor, which might cause imbalance relationship where the vendor is ‘stronger’ than you!
It’s our two cents. Hope it helps!