So if I understand this correctly:
Recharge: Reduces time for shields to recharge from 6 seconds to 5 seconds.
Shielding: Reduces shield recharge time from 2 seconds to 1 second.
Both reduce time by 1 second. So if you decide to use only one or the other, your shields will recharge in 7 seconds regardless. Strategically, this means that you can now use Mobility and Recharge instead of Mobility and Shielding, for example, since one is a Support Upgrade and the other is a Tactical Package, and gain more or less the same time advantage.
Or if you use Shielding and Recharge in conjunction, they will reduce the time by 2 seconds, from 8 seconds to 6 seconds.