# Can't explain double lines in graph

**URL:** <https://discourse.nodered.org/t/cant-explain-double-lines-in-graph/57410>\
**Category:** General\
**Created:** [28 January 2022 14:53 UTC](https://discourse.nodered.org/t/cant-explain-double-lines-in-graph/57410 "2022-01-28T14:53:16Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![maru](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/maru/32/99601_2.png) [@maru](https://discourse.nodered.org/u/maru)\
**Post date:** [28 January 2022 14:53 UTC](https://discourse.nodered.org/t/cant-explain-double-lines-in-graph/57410/1 "2022-01-28T14:53:16Z")

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Hi,

My dashboard shows double lines which is not the intention. What is the reason that a 2nd line appears and how do I remove it?

![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/7/6/76e0a37790c44428cfef09bcf7d05aa55f7d2f7e.png)  
 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/0/0/00541a716738c0b270fb99d1e97f78237d6e3064.png)

The data comes via MQTT ...

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/7/c/7c79572c01320329e86871087a28ef2e408a1359.png)

and is linked to my node-RED dashboard.

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/9/4/9487b8ee3b6032a7c09e1cf0b4be5c183ea93343.png)

These are the settings from my CO2 dashboard node ...

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/d/e/de09386ce22d6ccb3b70575801820e4a8aedfac5.png)

and the Temperature dashboard node.

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/5/1/51c45a0d0fd89c4ae3200f431bc0b76a5a59f166.png)

Thank you,

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<div class="post-metadata">

**Author:** ![mickym2](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/mickym2/32/36128_2.png) [@mickym2](https://discourse.nodered.org/u/mickym2)\
**Post date:** [28 January 2022 15:21 UTC](https://discourse.nodered.org/t/cant-explain-double-lines-in-graph/57410/2 "2022-01-28T15:21:06Z")

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A 2nd line only appears when you have a different topic. So either you find out, filter out different topics etc.

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**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [28 January 2022 15:32 UTC](https://discourse.nodered.org/t/cant-explain-double-lines-in-graph/57410/3 "2022-01-28T15:32:34Z")

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To check whether you have two different topics add a debug node, set to output Complete Message, showing what is going to the chart and check the topic values there.

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**Author:** ![dceejay](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dceejay/32/38_2.png) [@dceejay](https://discourse.nodered.org/u/dceejay)\
**Post date:** [28 January 2022 16:51 UTC](https://discourse.nodered.org/t/cant-explain-double-lines-in-graph/57410/4 "2022-01-28T16:51:49Z")

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or turn on show legend in the chart nodes and it should show the topics in the chart

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**Author:** ![maru](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/maru/32/99601_2.png) [@maru](https://discourse.nodered.org/u/maru)\
**Post date:** [28 January 2022 18:42 UTC](https://discourse.nodered.org/t/cant-explain-double-lines-in-graph/57410/5 "2022-01-28T18:42:39Z")

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I think it was a different topic. I disconnected a few other sensors from the flow and now see the correct lines.  
Thanks everyone for the advice

![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/5/1/515cdae440c02a71d6fa3af19cf73bf034e1ef66.png)

![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/8/7/871b49f18b6aad5eb3d3e4eb9a40a57c21792bff.png)

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [11 February 2022 18:42 UTC](https://discourse.nodered.org/t/cant-explain-double-lines-in-graph/57410/6 "2022-02-11T18:42:58Z")

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