Aynı klasörde duran kopyalar kolayca karışabilir.

A natural breakdown is:

• Aynı = same
• klasörde = in the folder
• duran = standing / staying / located
• kopyalar = copies
• kolayca = easily
• karışabilir = can get mixed up / may get mixed up

So the structure is:

• Aynı klasörde duran kopyalar = the copies that are in the same folder
• kolayca karışabilir = can easily get mixed up

In other words, aynı klasörde duran describes kopyalar.

Duran comes from the verb durmak.

In many beginner contexts, durmak is taught as to stand or to stop, but in real Turkish it can also mean something like:

• to stay
• to remain
• to be situated
• to be sitting/located somewhere

So in this sentence, duran kopyalar means:

• copies that are sitting there
• copies that are kept there
• copies located there

It does not necessarily mean they are literally “standing” in a physical sense.

Because duran is being used as a participle that modifies a noun.

• duruyor = is standing / is staying
  This is a finite verb form and could be the main verb of a sentence.
• duran = that stands / that is staying / that is located
  This is a participle, so it works like an adjective.

Compare:

• Kopyalar klasörde duruyor. = The copies are in the folder.
• Klasörde duran kopyalar = the copies that are in the folder

So duran is used because Turkish often replaces a relative clause like that are in the folder with a participle phrase.

It is a noun phrase meaning:

• the copies that are in the same folder

Piece by piece:

• aynı modifies klasörde duran
• klasörde duran modifies kopyalar

A very literal English-style unpacking would be:

• copies standing/staying in the same folder

More natural English would be:

• copies in the same folder
• copies located in the same folder

The ending -de / -da is the locative case, meaning in / at / on depending on context.

So:

• klasör = folder
• klasörde = in the folder

The form is -de here because of vowel harmony and consonant voicing rules.

This is very common in Turkish:

• evde = in the house
• okulda = at school
• masada = on the table
• klasörde = in the folder

Aynı is an indeclinable modifier in this kind of use. It means same and directly comes before the noun or noun phrase it modifies.

Examples:

• aynı ev = the same house
• aynı klasör = the same folder
• aynı klasörde = in the same folder

So you do not add an adjective ending to aynı here. The case ending goes on the noun:

• klasör → klasörde

Karışabilir is built from:

• karış- = get mixed up / become confused / get jumbled
• -abil- = can / may / be able to
• -ir = aorist/general statement ending

So karışabilir means:

• can get mixed up
• may get mixed up
• might get confused with one another

In this sentence, it expresses possibility, not certainty.

So the idea is:

• Copies in the same folder can easily get mixed up.

This is a very important distinction.

• karışmak = to get mixed up, to become confused, to be mixed together
  This is usually intransitive.
• karıştırmak = to mix up, to confuse, to stir
  This is usually transitive.

Examples:

• Dosyalar karıştı. = The files got mixed up.
• Dosyaları karıştırdım. = I mixed up the files.

In your sentence, kopyalar are the thing experiencing the mixing/confusion, so karışabilir is the correct choice.

In Turkish, when the subject is already clearly plural, the verb often stays in the singular third-person form.

So this is completely normal:

• Kopyalar karışabilir. = The copies can get mixed up.

Turkish does not require the same kind of subject-verb agreement that English does in this situation.

The plural is already shown by:

• kopya = copy
• kopyalar = copies

That is enough.

Kolayca is an adverb meaning easily. In Turkish, adverbs commonly appear before the verb they modify.

So:

• kolayca karışabilir = can easily get mixed up

This word order is very natural in Turkish.

You could think of the sentence pattern as:

• subject phrase + adverb + verb

They are related, but not identical in usage.

• kolay = easy / easily depending on context, but mainly an adjective
• kolayca = easily
• kolaylıkla = easily, with ease

In this sentence, kolayca is a very natural adverb choice.

Examples:

• Bu iş kolay. = This job is easy.
• Bu iş kolayca yapılır. = This job is done easily.
• Bu iş kolaylıkla yapılır. = This job is done with ease.

So kolayca here is simply the adverb easily.

Turkish does not have a direct article system like English the and a/an.

Whether something is understood as definite or indefinite often depends on context.

So kopyalar can mean:

• copies
• the copies

And aynı klasörde duran kopyalar can naturally be understood as:

• copies in the same folder
• the copies that are in the same folder

English usually forces you to choose, but Turkish often leaves that to context.

Yes, that is closer to the Turkish structure, but it sounds unnatural in English.

A more natural English rendering would be:

• Copies in the same folder can easily get mixed up.
• Copies located in the same folder can easily get mixed up.
• Copies kept in the same folder can easily get mixed up.

So the literal structure is useful for learning, but the natural translation is smoother.

Yes, Turkish word order is somewhat flexible, but this version is the most neutral and natural.

The standard order here is:

• descriptive phrase
• subject noun
• adverb
• verb

So:

• Aynı klasörde duran kopyalar kolayca karışabilir.

If you move things around, you may change the emphasis.

For example, putting kolayca elsewhere might sound marked or stylistically different. For learners, the original order is the best one to imitate.