Emails are only reported once

When scanning the following text, the detection of `daniel@haxx.se` is only returned once in the results while it appears multiple times in the file.

`scancode -ce --json-pp -`

```
Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
Upstream-Name: curl
Source: http://curl.haxx.se

Files: *
Copyright: 1996-2015, Daniel Stenberg
License: curl

Files: lib/vtls/axtls.*
Copyright: 2010, DirecTV
2010-2015, Daniel Stenberg
License: curl

Files: lib/vtls/darwinssl.*
Copyright: 2012-2014, Nick Zitzmann
2012-2015, Daniel Stenberg
License: curl

Files: lib/curl_rtmp.*
Copyright: 2010, Howard Chu
License: curl

Files: lib/vtls/schannel.*
Copyright: 2012-2014, Marc Hoersken
2012, Mark Salisbury
2012-2015, Daniel Stenberg
License: curl
```

Results:

```json
"emails": [
{
"email": "daniel@haxx.se",
"start_line": 6,
"end_line": 6
},
{
"email": "nickzman@gmail.com",
"start_line": 15,
"end_line": 15
},
{
"email": "hyc@highlandsun.com",
"start_line": 20,
"end_line": 20
},
{
"email": "info@marc-hoersken.de",
"start_line": 24,
"end_line": 24
},
{
"email": "mark.salisbury@hp.com",
"start_line": 25,
"end_line": 25
}
],
```