Equivant mass of double salt What is the equivalent mass of double salt like dolomite? And what if the double salt is hydrated?

Is a double salt taken as a single unit while equating the gram equivalent in any reaction?
For example, in reaction

$$\ce{CaCO3.MgCO3 + 4 HCl -&gt; CaCl2 + MgCl2 + 2 CO2}$$

is

$$\frac{\text{wt of dolomite}}{\text{eq wt of dolomite}} = \frac{\text{wt of}~\ce{CO2}}{\text{eq wt of}~\ce{CO2}}?$$
$\ce{CaCO3.MgCO3}$ reacts with $\ce{4 HCl}$, therefore $m_\mathrm{eq}=m/4$.
$\ce{CaCO3}$ reacts with $\ce{2 HCl}$, therefore $m_\mathrm{eq}=m/2$.
$\ce{MgCO3}$ reacts with $\ce{2 HCl}$, therefore $m_\mathrm{eq}=m/2$.
$\ce{Na2CO3.10 H2O}$ reacts with $\ce{2 HCl}$, therefore $m_\mathrm{eq}=m/4$.
$\ce{1 CO2}$ of carbonate origin is released by $\ce{2 HCl}$, therefore $m_\mathrm{eq}=m/2$.