Search for a Two-Higgs-Boson Doublet Using a Simplified Model in <span class="aps-inline-formula"><math display="inline"><mi>p</mi><mover accent="true"><mi>p</mi><mo>?</mo></mover></math></span> Collisions at <span class="aps-inline-formula"><math display="inline"><msqrt><mi>s</mi></msqrt><mo mathvariant="bold">=</mo><mn>1.96</mn><mtext>?</mtext><mtext>?</mtext><mi>TeV</mi></math></span>