Copying template tag issue

using V7.6.6, when copying a template using copy& paste, the copied tag does not copy with a proper incremented value:

tag to be copied using copy & paste:
[attachment=1]ScreenHunter_199 May. 31 07.00.jpg[/attachment]

expect tag to be copied as 11-YS-35-10-010, but copies as:

[attachment=0]ScreenHunter_200 May. 31 07.00.jpg[/attachment]

not a real issue, but it took me a while to figure where my copied tags were disappearing to, as I expected them to be listed as the next incremental value.