You can try using plugins copy and relabel to achieve this. Example configuration looks like this.
//One Source
<source>
@type tail
tag service
path /tmp/l.log
format json
read_from_head true
</source>
//Now Copy Source Events to 2 Labels
<match service>
@type copy
<store>
@type relabel
@label @data
</store>
<store>
@type relabel
@label @pi2
</store>
</match>
//@data Label, you can perform desired filter and output file
<label @data>
<filter service>
...
</filter>
<match service>
@type file
path /tmp/out/data
</match>
</label>
//@pi2 Label, you can perform desired filter and output file
<label @pi2>
<filter service>
...
</filter>
<match service>
@type file
path /tmp/out/pi
</match>
</label>
This Routing examples article has few more ways to do it by re-writing tag etc., but for me I like working with labels and above looks simple.