[CommonHTML] problem with labeled equations

Due to this SO question, I noticed a problem with labels in the CommonHTML output.

The following example does have the labels float to the right/left (but does in HTML-CSS and SVG) -- but each table individually renders correctly.

<math display="block">
    <mtable side='left'>
        <mlabeledtr>
            <mtd>
                <mtext>(1)</mtext>
            </mtd>
            <mtd>
                <mi>X</mi>
            </mtd>
        </mlabeledtr>
    </mtable>
    <mspace linebreak="newline" />
    <mtable>
        <mlabeledtr>
            <mtd>
                <mtext>(2)</mtext>
            </mtd>
            <mtd>
                <mi>Y</mi>
            </mtd>
        </mlabeledtr>
    </mtable>
</math>