Duplicate file x times in command shell

Your shell code has two issues:

1. The echo should not be there.
2. The variable $i is mistyped as $1 in the destination file name.

To make a copy of a file in the same directory as the file itself, use

cp thefile thecopy

If you insert anything else in there, e.g.

cp thefile theotherthing thecopy

then it is assumed that you'd like to copy thefile and theotherthing into the directory called thecopy.

In your case, it specifically looks for a file called test.ogg and one named echo to copy to the directory test$1.ogg.

The $1 will most likely expand to an empty string. This is why, when you delete the echo from the command, you get "test.ogg and test.ogg are the same files"; the command being executed is essentially

cp test.ogg test.ogg

This is probably a mistyping.

In the end, you want something like this:

for i in {1..100}; do cp test.ogg "test$i.ogg"; done

Or, as an alternative

i=0
while (( i++ < 100 )); do
  cp test.ogg "test$i.ogg"
done

Or, using tee:

tee test{1..100}.ogg <test.ogg >/dev/null

Note: This would most likely work for 100 copies, but for thousands of copies it may generate a "argument list too long" error. In that case, revert to using a loop.

for i in {1..100}; do cp test.ogg "test_$i.ogg" ; done

Short and precise

< test.ogg tee test{1..100}.ogg

or even better do

tee test{1..100}.ogg < test.ogg >/dev/null

see tee command usage for more help.

Update

as suggested by @Gilles, using tee has the defect of not preserving any file metadata. To overcome that issue, you might have to run below command after that:

cp --attributes-only --preserve Source Target