Take a look at the fonts used (Document > Properties > Fonts) - I cannot explain except that they are a temporary font type in the pdf's.
Read this about glyphs
Please check to be sure your links are waht you think they are. That first one is to a PDF made with Ghostscript. It also is the only one I can copy text from and paste into ID. It's PDF 1.3, the one exported from ID is PDF 1.4, and, and the one from Distiller is PDF1.5, which may have something to do with it.
The distilled file has dozens of Identity-H encoded fonts that look like they might be a custom font, the exported file has only 5, and the ghostsctript file has waht looks like the same five, but they are "custo" encoded. What fonts are you using ?
I am not using any fonts.
I started with that PDF, which I can copy and paste text from.
Then I brought it into In Design CS 5.5 (using the "place" function, + D)
Then, no matter what I did to export (I tried exporting, and I also tried "printing" to postscript file) the text can no longer be copied.
Are you creating a tagged PDF on export? If not, try that.
But I warn you, what you are trying to do is not what PDF is intended for and having this happen is not all that unheard of.
Have you tried saving the original PDF oout to another format like Word wher you can edit the text, then place that?
I don't have Word.
By the way, PDF's are bizarre.
I exported a 536 page PDF from In Design, and it was 5MB.
Then, I broght it back into IN Design on an 8.5x11 and exported, and it was 260MB !!!!!!
I give up.