@srg36 is correct. Single source is a little risky, but it is a necessary evil while launching a new product to market. The project team does not have enough time to on board a secondary source in most projects. To mitigate the risk, the  R&D project team should order/keep 6 months plus (depending on shelf life) of stock on hand for production. Once the product is launched and transferred to Operations from R&D, the Operations group can focus on finding a second source.

Using different components from the same company does not completely solve the issue of dual sourcing, because those two components are not completely independent. Most likely the two chemicals are made in the same location. So if something happens to that production location, like you said in your post, then the production of both components will be stopped and that means that your company cannot produce the finished product. Even if the two components are produced in different locations you are still dependent on that company staying in business. Companies fail for many different reasons, and if a company that produces the key components for a product goes under then you are back to the beginning having to identify new sourcing partners. In the end dual sourcing boils down to decreasing the odds that any one event can knock your production offline, whilst souring different components can mitigate that risk, there are better ways to mitigate these risks.