Your attack roll uses a specific weapon; when dual-wielding you will use one weapon and then the other
The rules on Two-Weapon Fighting state:
When you take the Attack action and attack with a light melee weapon that you're holding in one hand, you can use a bonus action to attack with a different light melee weapon that you're holding in the other hand. You don't add your ability modifier to the damage of the bonus attack, unless that modifier is negative [...]
This feature/process (available to all characters) requires you to wield two light weapons and you attack with each separately.
Let's say only one weapon is +1 and magical, then only the attack made using that weapon would bypass resistances to damage from non-magical attacks and only that weapon would receive the +1 to its attack and damage rolls. Your next attack would be made with the non-magical weapon and would receive no such benefits.
In your case both weapons are +1 and magical. Thus each attack will receive +1 to its attack and damage rolls, and both can overcome resistances. Neither attack will receive any sort of +2 to its attack and damage rolls.