Solve this differential equation?

(Edited to add: I may have solved my problem now. See end of post.)

This does not work (edited to fix a mistake of mine):

DSolve[{
  0 == -voltageC0[t] - 2*voltageC0''[t] + 2*voltageC1''[t],
  0 == -voltageC1[t] - 2*voltageC1''[t] + 2*voltageC0''[t]
  }, voltageC0[t], t]

Mathematica replies:

DSolve::overdet: There are fewer dependent variables than equations,
so the system is overdetermined.

I cannot make sense of that response from Mathematica. I see two dependent variables, and I see two equations. Two equals two. What is the meaning of Mathematica’s response to my query?

Edited to add: This attempt apparently succeeds:

DSolve[{
  0 == -voltageC0[t] - 2*voltageC0''[t] + 2*voltageC1''[t],
  0 == -voltageC1[t] - 2*voltageC1''[t] + 2*voltageC0''[t]
  }, {voltageC0, voltageC1}, t]

The large constant-numerical-values appearing in the solution do surprise me though.

From your equation you can deduce that voltageC0 is the same as voltageC1. You only have one differential equation with two unknowns voltage01 and voltage10.

Thanks. I believe adding the two equations shows actually that

0==voltageC0 +voltageC1

However, when I ensure the number of equations matches the number of unkowns (as shown in my now-updated original post), I get a different cryptic error-message from Mathematica. Can anyone make sense of Mathematica’s response to my query?