There "might" be the slightest of mismatch due to sun fade. Maybe. But the biggest "mismatch" will come not from the color but instead from how you apply and blend it in (prep and then wetsand/buff, etc).
What Dennis said is true. Once you repair the damage and prime it then you spay medium coats ( 2- 3) to cover the primed area then you blend out further ( spay a very light coat as you move further the coat should much less). When it's done you spray clear on the whole area, preferably all the cover so you don't have an edge, with time you will see that edge more .
If you never sprayed before and you want a good job take it to a pro like a car panel shop, they will even mix their own paint and you will never see the difference.