First make this at the start of your code:

local carbine = false

Then change your 2 events into this one event:

RegisterNetEvent("UnlockCarbine")
AddEventHandler("UnlockCarbine", function()
    local weapon = GetHashKey("WEAPON_CARBINERIFLE")
	local ped = GetPlayerPed(PlayerId())
    carbine = not carbine
    if carbine then
	    GiveWeaponToPed(ped, weapon, 1000, false, true)
    else
        RemoveWeaponFromPed(ped, weapon)
    end
end)

That should work, have not tested it though.