Input the same contig name twice in CAP3

To reproduce this bug:

1. Add input files into CAP3, for example, 1.fa, 2.fa, 3.fa and press "Run". The result contig name will be "3.cap.ace".
2. Add input files into CAP3, for example, 4.fa, 5.fa, 3.fa and press "Run". The result contig name will be "3.cap.ace". But error occurs:

[20:46:07] 'CAP3SupportTask' task failed: Subtask

{Opening view for document: 3.cap.ace}

is failed: Subtask

{Adding document to project: D:/Documents/tests/3.cap.ace}

is failed: Document is already added to the project D:/Documents/tests/3.cap.ace.

But it is another document with the same name. Maybe it would be better to ask a user if he would like to rewrite the existent file, rename the new file or cancel.