How to multiple install telegraf in redhat
Assuming you are in RHEL7, you would need to make a copy the systemd unit files. However, I don’t really recommend it except in a few narrow cases, you can almost always run a single Telegraf per system and it really complicates upgrades.
Can you tell me a little bit about why you want to run multiple Telegraf’s on one system, I might be able to help you find a shared configuration.

rabbitmq push to telegraf, and all telegraf push to 1 influxdb
Have you tried defining 3 amqp_consumer inputs and a single influxdb output? Then you could run this workload in a single Telegraf instance:
[[inputs.amqp_consumer]]
# ... snip ...
[[inputs.amqp_consumer]]
# ... snip ...
[[inputs.amqp_consumer]]
# ... snip ...
[[outputs.influxdb]]
# ... snip ...

