Lyx handling of \begin{align} and duplicate \tag with amsmath?

I am trying Lyx. I started Lyx and asked it to import this plain Latex file:

\documentclass[12pt]{article}%
\usepackage{amsmath}
\begin{document}

\begin{align}
A  &= B+C   \tag{33}\\
D  &= F+G   \tag{34}
\end{align}

\end{document}

However it seems Lyx adds its own tags to each equation, giving this result on the screen

This seems to be just a configuration issue, as I saw few things about it, but I do not understand what the issue exactly.

There is a related question here Automatic equation numbering in LyX but I tried the suggestion there for this case, and I still see the double tags in there.

I also tried to import the same latex file, without the amsmath package, like this

\documentclass[12pt]{article}%
%%%%%%   \usepackage{amsmath}  %% comment out for Lyx
\begin{document}
\begin{align}
A  &= B+C   \tag{33}\\
D  &= F+G   \tag{34}
\end{align}
\end{document}

But still the double \tag showed up.

Could some one please explain (in simple terms, as I am newbie in Lyx) what I need to do to remove the tag that Lyx adds and tell it to use the original tags in the latex file?

I am trying to test Lyx to see how it handles some of my Latex files, and I want to keep the same equation numbers and not change them.

• This is only a problem in the LyX GUI, if you view the PDF your custom numbers are used. – Torbjørn T. Feb 26 '14 at 10:58
• not being a lyx user, but being quite familiar with the coding of math, i'm confused by the contention that amsmath isn't used, since i don't know of any other package that defines the align environment. perhaps this refers only to the fact of commenting out the \usepackage line in the imported latex file? – barbara beeton Feb 26 '14 at 14:34