Ignnore last value in a column within a grouped set of values

Hey,
I’m trying to get the duration of how long a workorder was within a process. To get this i have two time series which i call in two seperate tabels. I then unionize it with the Union() function.
When i use the group() function and then events.duration() the last value is the duration from the last time the workorder ID was written and the _stop time. Thats why i want to ignore the last value.
Is there a way to do this?

Here is the Query i use:
import “contrib/tomhollingworth/events”

toString = (tables=<-) =>

 tables

|> map(fn:(r) => ({ r with ID: string(v: r.ID) }))

tab1 = from(bucket: “zone/autogen”)

|> range(start: 2021-01-01T00:00:00Z)

|> filter(fn: (r) =>

r._measurement == "M1"

)

|> pivot(

rowKey:["_time"],

columnKey: ["short","_field"],

valueColumn: "_value"

)

|>keep(columns:["_time",“ID_value”,"_stop"])

|>rename(columns:{ID_value:“ID”})

|>toString()

tab2 = from(bucket: “zone/autogen”)

|> range(start: 2021-01-01T00:00:00Z)

|> filter(fn: (r) =>

r._measurement == “M2” and

r.short == “ID_production”

)

|> pivot(

rowKey:["_time"],

columnKey: [“short”,"_field"],

valueColumn: “_value”

)

|> keep(columns:["_time",“ID_production_value_str”,"_stop"])

|> rename(columns: {“ID_production_value_str”: “ID”})

|>toString()

union(

tables:[tab1,tab2],

)

|>group(columns:[“ID”])

|>events.duration(

unit: 1m,

columnName: “duration”,

timeColumn: “_time”,

stopColumn: “_stop”

)

What i get is the following:

As you can see the last value in the duration column is to high.
I hope somone can help me with this.

I use InfluxDB 2.0 and Grafana 7.5 to visualize the data

The Solution: define the stopColumn : “_time”. The last value will be 0