If you copied the glyph from the Glyph window, then all you got were the outlines. Copy and paste the glyph from the Font WIndow and all of the information should be included. Then there is always "Paste Special".

jmontalbano - thanks for your answer. I have copied the glyph from the Font windows, and still, hinting is not the same for the two glyphs. I have also tried the 'Paste Special' option, selecting all the check buttons. When I have open the new glyph and try to see its hinting,
FontLab give me a message: "current glyph doesn't match TrueType requirements", and ask if I want to fix this. I choose to fix it, and the same problem - hinting is not exactly the same for the two glyphs.

You might be trying to copy hinting information that is not supported by Fontlab.

You could try "Generate Glyphs". Using the original glyph name followed by a period and suffix of your choice will force FL to reference the original glyph. Once the new glyph is present, you can rename it if necessary.

I suppose the really simple solution would be to create a new glyph and place the original glyph as a Component.

jmontalbano, Thanks a lot for your help - I added the original as a component and it works perfect. I'm new to font editors and didn't know about this option.

It seems to me that DejaVu sans is manually hinted, so when copy an outline of a glyph, you get an original glyph manually hinted, and a second one auto hinted. And when making a full copy from the Font Window, you get a message indicating that this operation will cause a loss of the font's original OpenType tables.

I'm curious why you would need a duplicate glyph in an alternate position.

I had to create a composite glyph which does not exists in the font, only its elements
exist. I.e, now I know that there is such a concept, 'a composite glyph'.