Multiple senders of same type gives: EchoSender already exists in this element

**Describe the bug**
Using the following valid configuration:
```






```
Gives:
Parsing error found in XML
EchoSender already exists in this element

**Reporter**
Jaco de Groot

**Category**
Use the following Tags to categorize your bug report

- Editor

**To Reproduce**
Steps to reproduce the behavior:

1. Add a sender like mentioned above
2. See error at the right bottom of the screen

**Expected behavior**
No error

**Screenshots**
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**Additional context**
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