When dragging a file (e.g. an image) from a website to dolphin, dolphin will download the file with a .part extension and then attempt to rename it. However, if a file with the target name already exists, at this point dolphin will display an error message instead of giving an option to overwrite.

Reproducible: Always

Steps to Reproduce:
1. Create a file with the same name as one on the internet
2. Drag the internet file into the same directory and click "Copy Here"
3. Wait for dolphin to download the file. Once done, a dialog will appear, saying "Could not rename partial file /path/to/file. Please check permissions" (this occurs regardless of permissions)
4. Click "Retry" 
5. Now a "File already exists" dialog will appear, albeit without an option to rename the file. Click either "resume" or "overwrite" (both do the same thing, i.e. nothing). 
6. A second "File already exists" dialog will appear, this time with an option to rename. Click "overwrite"
7. File will finally be overwritten as expected

Actual Results:  
Three dialogs appeared throughout the course of overwriting a file

Expected Results:  
Only the final dialog need have been shown, with the option to rename or overwrite.

I'm using dolphin 15.08.2 using KDE frameworks 5.15.0 on Archlinux (openbox).