Toyota Repair Problems? Ask a Mechanic for Answers ASAP
How many miles are on the car? Was the ride up until this point very smooth without any bouncing in the front end? Is there any leaking from the right front strut that was not damaged?
Generally speaking it's recommended to replace struts in pairs. However the only difference that would be in your situation where the ride is normal and not bouncy and there's no leaking from the right strut. If they are using a Toyota strut you should be fine just replacing the one. However if they are using an aftermarket strut this becomes a problem because they're not built the same as the Toyota struts and the ride quality will suffer. Most insurance companies will not replace the other side due to ride quality or issues like that you're barking up the wrong tree dealing with this insurance company to get them to replace the other strut. Just make sure the strut that was damaged is replaced by factory Toyota strut. They'll probably cry about that too because they're not cheap.
If there's no leaking from the right front strut in the ride has been top-notch personally if it was my vehicle I would not spend the money. But I more frugal than most. If you want to spend the extra $250-$350 to have the strut replaced by the dealer so that it matches the new Toyota strut and is not going to set you back then you know from the get-go both are brand-new and have the alignment done and you won't have any worries for another 150,000 miles.